diff --git a/src/neo-vm/Debugger.cs b/src/neo-vm/Debugger.cs
new file mode 100644
index 00000000..8518e3ef
--- /dev/null
+++ b/src/neo-vm/Debugger.cs
@@ -0,0 +1,78 @@
+using System.Collections.Generic;
+
+namespace Neo.VM
+{
+    public class Debugger
+    {
+        private readonly ExecutionEngine engine;
+        private readonly Dictionary<byte[], HashSet<uint>> break_points = new Dictionary<byte[], HashSet<uint>>(new HashComparer());
+
+        public Debugger(ExecutionEngine engine)
+        {
+            this.engine = engine;
+        }
+
+        public void AddBreakPoint(byte[] script_hash, uint position)
+        {
+            if (!break_points.TryGetValue(script_hash, out HashSet<uint> hashset))
+            {
+                hashset = new HashSet<uint>();
+                break_points.Add(script_hash, hashset);
+            }
+            hashset.Add(position);
+        }
+
+        public void Execute()
+        {
+            engine.State &= ~VMState.BREAK;
+            while (!engine.State.HasFlag(VMState.HALT) && !engine.State.HasFlag(VMState.FAULT) && !engine.State.HasFlag(VMState.BREAK))
+            {
+                engine.ExecuteNext();
+                if (engine.State == VMState.NONE && engine.InvocationStack.Count > 0 && break_points.Count > 0)
+                {
+                    if (break_points.TryGetValue(engine.CurrentContext.ScriptHash, out HashSet<uint> hashset) && hashset.Contains((uint)engine.CurrentContext.InstructionPointer))
+                        engine.State = VMState.BREAK;
+                }
+            }
+        }
+
+        public bool RemoveBreakPoint(byte[] script_hash, uint position)
+        {
+            if (!break_points.TryGetValue(script_hash, out HashSet<uint> hashset)) return false;
+            if (!hashset.Remove(position)) return false;
+            if (hashset.Count == 0) break_points.Remove(script_hash);
+            return true;
+        }
+
+        public void StepInto()
+        {
+            if (engine.State.HasFlag(VMState.HALT) || engine.State.HasFlag(VMState.FAULT)) return;
+            engine.ExecuteNext();
+            if (engine.State == VMState.NONE)
+                engine.State = VMState.BREAK;
+        }
+
+        public void StepOut()
+        {
+            engine.State &= ~VMState.BREAK;
+            int c = engine.InvocationStack.Count;
+            while (!engine.State.HasFlag(VMState.HALT) && !engine.State.HasFlag(VMState.FAULT) && !engine.State.HasFlag(VMState.BREAK) && engine.InvocationStack.Count >= c)
+                engine.ExecuteNext();
+            if (engine.State == VMState.NONE)
+                engine.State = VMState.BREAK;
+        }
+
+        public void StepOver()
+        {
+            if (engine.State.HasFlag(VMState.HALT) || engine.State.HasFlag(VMState.FAULT)) return;
+            engine.State &= ~VMState.BREAK;
+            int c = engine.InvocationStack.Count;
+            do
+            {
+                engine.ExecuteNext();
+            } while (!engine.State.HasFlag(VMState.HALT) && !engine.State.HasFlag(VMState.FAULT) && !engine.State.HasFlag(VMState.BREAK) && engine.InvocationStack.Count > c);
+            if (engine.State == VMState.NONE)
+                engine.State = VMState.BREAK;
+        }
+    }
+}
diff --git a/src/neo-vm/ExecutionEngine.cs b/src/neo-vm/ExecutionEngine.cs
index 940320dc..f529184a 100644
--- a/src/neo-vm/ExecutionEngine.cs
+++ b/src/neo-vm/ExecutionEngine.cs
@@ -57,7 +57,6 @@ public class ExecutionEngine : IDisposable
         private bool is_stackitem_count_strict = true;
 
         private readonly IScriptTable table;
-        private readonly Dictionary<byte[], HashSet<uint>> break_points = new Dictionary<byte[], HashSet<uint>>(new HashComparer());
 
         public IScriptContainer ScriptContainer { get; }
         public ICrypto Crypto { get; }
@@ -67,7 +66,7 @@ public class ExecutionEngine : IDisposable
         public ExecutionContext CurrentContext => InvocationStack.Peek();
         public ExecutionContext CallingContext => InvocationStack.Count > 1 ? InvocationStack.Peek(1) : null;
         public ExecutionContext EntryContext => InvocationStack.Peek(InvocationStack.Count - 1);
-        public VMState State { get; protected set; } = VMState.BREAK;
+        public VMState State { get; internal protected set; } = VMState.BREAK;
 
         public ExecutionEngine(IScriptContainer container, ICrypto crypto, IScriptTable table = null, IInteropService service = null)
         {
@@ -77,16 +76,6 @@ public ExecutionEngine(IScriptContainer container, ICrypto crypto, IScriptTable
             this.Service = service;
         }
 
-        public void AddBreakPoint(byte[] script_hash, uint position)
-        {
-            if (!break_points.TryGetValue(script_hash, out HashSet<uint> hashset))
-            {
-                hashset = new HashSet<uint>();
-                break_points.Add(script_hash, hashset);
-            }
-            hashset.Add(position);
-        }
-
         #region Limits
 
         /// <summary>
@@ -207,7 +196,7 @@ public void Execute()
                 ExecuteNext();
         }
 
-        protected void ExecuteNext()
+        internal protected void ExecuteNext()
         {
             if (InvocationStack.Count == 0)
             {
@@ -225,11 +214,6 @@ protected void ExecuteNext()
                 {
                     State = VMState.FAULT;
                 }
-                if (State == VMState.NONE && InvocationStack.Count > 0)
-                {
-                    if (break_points.Count > 0 && break_points.TryGetValue(CurrentContext.ScriptHash, out HashSet<uint> hashset) && hashset.Contains((uint)CurrentContext.InstructionPointer))
-                        State = VMState.BREAK;
-                }
             }
         }
 
@@ -1307,47 +1291,5 @@ protected virtual bool PreExecuteInstruction()
         {
             return true;
         }
-
-        public bool RemoveBreakPoint(byte[] script_hash, uint position)
-        {
-            if (!break_points.TryGetValue(script_hash, out HashSet<uint> hashset))
-                return false;
-            if (!hashset.Remove(position))
-                return false;
-            if (hashset.Count == 0)
-                break_points.Remove(script_hash);
-            return true;
-        }
-
-        public void StepInto()
-        {
-            if (State.HasFlag(VMState.HALT) || State.HasFlag(VMState.FAULT)) return;
-            ExecuteNext();
-            if (State == VMState.NONE)
-                State = VMState.BREAK;
-        }
-
-        public void StepOut()
-        {
-            State &= ~VMState.BREAK;
-            int c = InvocationStack.Count;
-            while (!State.HasFlag(VMState.HALT) && !State.HasFlag(VMState.FAULT) && !State.HasFlag(VMState.BREAK) && InvocationStack.Count >= c)
-                ExecuteNext();
-            if (State == VMState.NONE)
-                State = VMState.BREAK;
-        }
-
-        public void StepOver()
-        {
-            if (State.HasFlag(VMState.HALT) || State.HasFlag(VMState.FAULT)) return;
-            State &= ~VMState.BREAK;
-            int c = InvocationStack.Count;
-            do
-            {
-                ExecuteNext();
-            } while (!State.HasFlag(VMState.HALT) && !State.HasFlag(VMState.FAULT) && !State.HasFlag(VMState.BREAK) && InvocationStack.Count > c);
-            if (State == VMState.NONE)
-                State = VMState.BREAK;
-        }
     }
 }
diff --git a/tests/neo-vm.Tests/VMJsonTestBase.cs b/tests/neo-vm.Tests/VMJsonTestBase.cs
index d51d826e..de3fdcf4 100644
--- a/tests/neo-vm.Tests/VMJsonTestBase.cs
+++ b/tests/neo-vm.Tests/VMJsonTestBase.cs
@@ -50,6 +50,7 @@ public void ExecuteTest(VMUT ut)
 
                 using (var engine = new ExecutionEngine(scriptContainer, Crypto.Default, scriptTable, service))
                 {
+                    Debugger debugger = new Debugger(engine);
                     engine.LoadScript(test.Script);
 
                     // Execute Steps
@@ -64,10 +65,10 @@ public void ExecuteTest(VMUT ut)
                                 {
                                     switch (run)
                                     {
-                                        case VMUTActionType.Execute: engine.Execute(); break;
-                                        case VMUTActionType.StepInto: engine.StepInto(); break;
-                                        case VMUTActionType.StepOut: engine.StepOut(); break;
-                                        case VMUTActionType.StepOver: engine.StepOver(); break;
+                                        case VMUTActionType.Execute: debugger.Execute(); break;
+                                        case VMUTActionType.StepInto: debugger.StepInto(); break;
+                                        case VMUTActionType.StepOut: debugger.StepOut(); break;
+                                        case VMUTActionType.StepOver: debugger.StepOver(); break;
                                     }
                                 }