diff --git a/src/PromptflowCSharp/Flow2/Flow2.cs b/src/PromptflowCSharp/Flow2/Flow2.cs
index 651660b003d..281cf3389ee 100644
--- a/src/PromptflowCSharp/Flow2/Flow2.cs
+++ b/src/PromptflowCSharp/Flow2/Flow2.cs
@@ -30,8 +30,12 @@ public Output Execute(Input inputs)
         {
             var output = new Output();
             // execution code: start
+            // sample node to call Tool in the same project
             var node1 = InternalTool.CallSimpleLLM(inputs.Prompt);
+
+            // sample node to call Tool in standalone tool project
             var node2 = SampleTool.SimpleLLM.CallSimpleLLM(node1);
+
             output.Out1 = node1;
             output.Out2 = node2;
             // execution code: end
diff --git a/src/PromptflowCSharp/Flow2/flow.dag.yaml b/src/PromptflowCSharp/Flow2/flow.dag.yaml
new file mode 100644
index 00000000000..b1095e8b82a
--- /dev/null
+++ b/src/PromptflowCSharp/Flow2/flow.dag.yaml
@@ -0,0 +1,25 @@
+inputs:
+  prompt:
+    type: string
+outputs:
+  out1:
+    type: string
+    reference: ${node1.output}
+  out2:
+    type: string
+    reference: ${node2.output}
+nodes:
+- name: node1
+  type: csharp
+  source:
+    type: func
+    path: InternalTool.CallSimpleLLM
+  inputs:
+    prompt: ${inputs.prompt}
+- name: node2
+  type: csharp
+  source:
+    type: func
+    path: SampleTool.SimpleLLM.CallSimpleLLM
+  inputs:
+    prompt: ${node1.output}
diff --git a/src/promptflow/promptflow/_sdk/csharp_sync.py b/src/promptflow/promptflow/_sdk/csharp_sync.py
new file mode 100644
index 00000000000..ca9c2b866c1
--- /dev/null
+++ b/src/promptflow/promptflow/_sdk/csharp_sync.py
@@ -0,0 +1,208 @@
+import re
+import sys
+from pathlib import Path
+
+import yaml
+
+from promptflow._utils.utils import camel_to_snake
+
+
+class Node:
+    def __init__(self, *, name, indent, source_func, inline_comment, inputs):
+        self._name = name
+        self._indent = indent
+        self._inputs = inputs
+        self._source_func = source_func
+        self._inline_comment = inline_comment
+
+    @classmethod
+    def from_yaml(cls, yaml: str, start: int, end: int):
+        return
+
+    @classmethod
+    def _parse_input(cls, input_str):
+        if "." not in input_str:
+            return f"${{{camel_to_snake(input_str)}.output}}"
+        else:
+            assert input_str.startswith("inputs.")
+            return f"${{inputs.{camel_to_snake(input_str.split('.', 1)[1])}}}"
+
+    @classmethod
+    def from_cs(cls, cs: str):
+        if len(cs.strip()) == 0:
+            return None
+        if cs.strip().startswith("//"):
+            return None
+
+        assert cs.count("=") == 1, f"Invalid line: {cs}"
+        clarification, call = cs.split("=")
+        indent = len(clarification) - len(clarification.lstrip())
+        pieces = re.split(r"\s+", clarification.strip())
+        if len(pieces) == 2:
+            # var nodeName = ToolFunc(inputs.InputName); // inline comment
+            output_cls, name = pieces
+
+            assert call.count(";") == 1, f"Invalid line: {cs}"
+            clear_call, inline_comment = call.split(";")
+            clear_call = re.sub(r"\s+", "", clear_call)
+
+            m = re.match(r"([a-zA-Z0-9.]+)\((.+)\)$", clear_call)
+            assert m, f"Invalid line: {cs}, error in parsing {clear_call}"
+
+            re.match(r"^(\s*)public\s+class\s+(\w+)\s*{\s*$", cs)
+            source_func = m.group(1)
+            inputs = [cls._parse_input(_in) for _in in m.group(2).split(",")]
+
+            return cls(
+                indent=indent,
+                name=name,
+                inline_comment=inline_comment,
+                source_func=source_func,
+                inputs=inputs,
+            )
+        elif len(pieces) == 1 and pieces[0].startswith("output."):
+            # output.OutputName = ToolFunc(inputs.InputName); // inline comment
+            return camel_to_snake(pieces[0].split(".", 1)[1]), cls._parse_input(call.strip().strip(";"))
+        else:
+            raise AssertionError(f"Invalid line: {cs}")
+
+
+class Graph:
+    def __init__(self, cs_path: str):
+        self._nodes = []
+        self._prefix, self._execution_code, self._suffix = self.split_code(
+            Path(cs_path).read_text(encoding="utf-8").splitlines()
+        )
+        self._execution_nodes, self._outputs = [], {}
+        for line in self._execution_code:
+            item = Node.from_cs(line)
+            if item is None:
+                continue
+            if isinstance(item, tuple):
+                self._outputs[item[0]] = item[1]
+            elif isinstance(item, Node):
+                self._execution_nodes.append(item)
+            else:
+                raise AssertionError(f"Invalid item: {item}")
+        self._inputs = self.gather_inputs_from_nodes()
+
+    def gather_inputs_from_nodes(self):
+        inputs = []
+        for node in self._execution_nodes:
+            if node is None:
+                continue
+            for reference in node._inputs:
+                m = re.match(r"^\${inputs\.(.+)}$", reference)
+                if m:
+                    inputs.append(m.group(1))
+        return inputs
+
+    @classmethod
+    def split_code(cls, lines: list[str]):
+        prefix, suffix = [], []
+
+        execution_code = []
+        execution_status = 0
+        for line in lines:
+            if execution_status == 0:
+                prefix.append(line)
+            elif execution_status == 1:
+                execution_code.append(line)
+            elif execution_status == 2:
+                suffix.append(line)
+
+            if line.strip() == "// execution code: start":
+                execution_status = 1
+            elif line.strip() == "// execution code: end":
+                suffix.append(execution_code.pop())
+                execution_status = 2
+
+        return prefix, execution_code, suffix
+
+    @classmethod
+    def from_yaml(cls, yaml: str):
+        return cls()
+
+    def dump_yaml(self, yaml_path: str):
+        obj = {
+            "inputs": {input_: {"type": "string"} for input_ in self._inputs},
+            "outputs": {k: {"type": "string", "reference": v} for k, v in self._outputs.items()},
+            "nodes": [],
+        }
+        for node in self._execution_nodes:
+            inputs_obj = {}
+            for item in node._inputs:
+                # seems that this can't be resolved from text
+                inputs_obj["prompt"] = item
+            obj["nodes"].append(
+                {
+                    "name": node._name,
+                    "type": "csharp",
+                    "source": {
+                        "type": "func",
+                        "path": node._source_func,
+                    },
+                    "inputs": inputs_obj,
+                }
+            )
+        yaml.dump(obj, Path(yaml_path).open("w"), indent=2, sort_keys=False)
+        return
+
+
+class Transformer:
+    def __init__(self, flow_cs: str):
+        self._flow_cs = Path(flow_cs).absolute()
+        flow_dir = self._flow_cs.parent.as_posix()
+        self._flow_dag_yaml = Path(f"{flow_dir}/flow.dag.yaml").absolute()
+        self._last_flow_dag_yaml = Path(f"{flow_dir}/.promptflow/transfer-backup/flow.dag.yaml").absolute()
+        self._last_flow_cs = Path(f"{flow_dir}/.promptflow/transfer-backup/Flow.cs").absolute()
+        self._last_flow_cs.parent.mkdir(parents=True, exist_ok=True)
+
+    def _backup(self):
+        if self._flow_dag_yaml.is_file():
+            self._last_flow_dag_yaml.write_bytes(self._flow_dag_yaml.read_bytes())
+        if self._flow_cs.is_file():
+            self._last_flow_cs.write_bytes(self._flow_cs.read_bytes())
+        return
+
+    def generate_flow_dag_yaml(self):
+        Graph(self._flow_cs.as_posix()).dump_yaml(self._flow_dag_yaml.as_posix())
+
+    def generate_flow_cs(self):
+        return
+
+    def _sync(self):
+        if not self._flow_dag_yaml.is_file() and not self._flow_cs.is_file():
+            print("No flow.dag.yaml or Flow.cs found.")
+            return
+
+        if not self._flow_dag_yaml.exists():
+            self.generate_flow_dag_yaml()
+            return
+        if not self._flow_cs.exists():
+            self.generate_flow_cs()
+            return
+
+        flow_dag_yaml_updated = self._flow_dag_yaml.read_bytes() != self._last_flow_dag_yaml.read_bytes()
+        flow_cs_updated = self._flow_cs.read_bytes() != self._last_flow_cs.read_bytes()
+
+        if flow_cs_updated and flow_dag_yaml_updated:
+            print("Support 1-side change sync only for now but both flow.dag.yaml and Flow.cs are updated.")
+            return
+
+        if not flow_cs_updated and not flow_dag_yaml_updated:
+            print("No change detected.")
+            return
+
+        if flow_cs_updated:
+            # TODO: update flow.dag.yaml
+            self.generate_flow_dag_yaml()
+
+    def sync(self):
+        self._sync()
+        self._backup()
+        return
+
+
+if __name__ == "__main__":
+    Transformer(sys.argv[1]).sync()
diff --git a/src/promptflow/promptflow/_sdk/data/transfer/EmptyFlow.cs.jinja2 b/src/promptflow/promptflow/_sdk/data/transfer/EmptyFlow.cs.jinja2
new file mode 100644
index 00000000000..4d4655d990d
--- /dev/null
+++ b/src/promptflow/promptflow/_sdk/data/transfer/EmptyFlow.cs.jinja2
@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Flow
+{
+    public class Flow2
+    {
+        public class Input
+        {
+            public string Prompt { get; set; } = string.Empty;
+        }
+
+        public class Output
+        {
+            public string Out1 { get; set; } = string.Empty;
+            public string Out2 { get; set; } = string.Empty;
+        }
+
+
+        public Flow2()
+        {
+
+        }
+
+        public Output Execute(Input inputs)
+        {
+            var output = new Output();
+            // execution code: start
+            var node1 = InternalTool.CallSimpleLLM(inputs.Prompt);
+            var node2 = SampleTool.SimpleLLM.CallSimpleLLM(node1);
+            output.Out1 = node1;
+            output.Out2 = node2;
+            // execution code: end
+            return output;
+        }
+    }
+}