diff --git a/test/src/main.rs b/test/src/main.rs
index 4b538f6094..d6a8187e70 100644
--- a/test/src/main.rs
+++ b/test/src/main.rs
@@ -148,6 +148,7 @@ fn main() {
     let mut test_results = Vec::new();
     let mut worker_running = worker_count;
     let mut done_specs = 0;
+    let mut started_sequential = false;
     while worker_running > 0 {
         if max_time > 0 && start_time.elapsed().as_secs() > max_time {
             // shutdown, specs running to long
@@ -155,6 +156,11 @@ fn main() {
             break;
         }
 
+        if worker_running == 1 && !started_sequential {
+            started_sequential = true;
+            workers.start_sequencial()
+        }
+
         let msg = match notify_rx.recv_timeout(Duration::from_secs(5)) {
             Ok(msg) => msg,
             Err(err) => {
@@ -590,9 +596,9 @@ fn all_specs() -> Vec<Box<dyn Spec>> {
         Box::new(CheckVmVersion2),
         Box::new(CheckVmBExtension),
         Box::new(RandomlyKill),
+        Box::new(SyncChurn),
     ];
     specs.shuffle(&mut thread_rng());
-    specs.insert(0, Box::new(SyncChurn) as Box<dyn Spec>);
     specs
 }
 
diff --git a/test/src/worker.rs b/test/src/worker.rs
index 4fec1ccd3f..88ae61624f 100644
--- a/test/src/worker.rs
+++ b/test/src/worker.rs
@@ -13,6 +13,7 @@ use std::time::Instant;
 #[derive(PartialEq, Eq)]
 pub enum Command {
     Shutdown,
+    StartSequencial,
 }
 
 /// Notify from worker
@@ -45,6 +46,9 @@ pub struct Worker {
     inbox: Receiver<Command>,
     outbox: Sender<Notify>,
     start_port: Arc<AtomicU16>,
+
+    sequencial_tasks: Arc<Mutex<Vec<Box<dyn Spec>>>>,
+    sequencial_worker: bool,
 }
 
 impl Clone for Worker {
@@ -54,13 +58,18 @@ impl Clone for Worker {
             inbox: self.inbox.clone(),
             outbox: self.outbox.clone(),
             start_port: Arc::clone(&self.start_port),
+            sequencial_tasks: Arc::clone(&self.sequencial_tasks),
+            sequencial_worker: self.sequencial_worker,
         }
     }
 }
 
+const SEQUENCIAL_TASKS: &[&str] = &["RandomlyKill", "SyncChurn"];
+
 impl Worker {
     pub fn new(
         tasks: Arc<Mutex<Vec<Box<dyn Spec>>>>,
+        sequencial_tasks: Arc<Mutex<Vec<Box<dyn Spec>>>>,
         inbox: Receiver<Command>,
         outbox: Sender<Notify>,
         start_port: Arc<AtomicU16>,
@@ -70,12 +79,16 @@ impl Worker {
             inbox,
             outbox,
             start_port,
+            sequencial_tasks,
+            sequencial_worker: false,
         }
     }
 
     /// start handle tasks
     pub fn start(self) -> JoinHandle<()> {
         thread::spawn(move || {
+            let mut start_sequencial_task = false;
+
             loop {
                 let msg = match self.inbox.try_recv() {
                     Ok(msg) => Some(msg),
@@ -88,20 +101,54 @@ impl Worker {
                     }
                 };
                 // check command
-                if Some(Command::Shutdown) == msg {
-                    self.outbox.send(Notify::Stop).unwrap();
-                    return;
+                match msg {
+                    Some(Command::StartSequencial) => {
+                        start_sequencial_task = true;
+                    }
+                    Some(Command::Shutdown) => {
+                        self.outbox.send(Notify::Stop).unwrap();
+                        return;
+                    }
+                    _ => {}
                 }
+
                 // pick a spec to run
-                let spec = match self.tasks.lock().pop() {
-                    Some(spec) => spec,
+
+                let task = self.tasks.lock().pop();
+                match task {
+                    Some(spec) => {
+                        // if spec.name() is RandomlyKill or SyncChurn, then push it to sequencial_tasks
+                        if SEQUENCIAL_TASKS.contains(&spec.name()) {
+                            info!("push {} to sequencial_tasks", spec.name());
+                            self.sequencial_tasks.lock().push(spec);
+                        } else {
+                            self.run_spec(spec.as_ref(), 0);
+                        }
+                    }
                     None => {
-                        self.outbox.send(Notify::Stop).unwrap();
-                        return;
+                        if self.sequencial_worker {
+                            info!("sequencial worker is waiting for command");
+                            if start_sequencial_task {
+                                match self.sequencial_tasks.lock().pop() {
+                                    Some(spec) => {
+                                        self.run_spec(spec.as_ref(), 0);
+                                    }
+                                    None => {
+                                        info!("sequencial worker has no task to run");
+                                        self.outbox.send(Notify::Stop).unwrap();
+                                        return;
+                                    }
+                                };
+                            } else {
+                                info!("sequencial worker is waiting for parallel workers finish");
+                                std::thread::sleep(std::time::Duration::from_secs(1));
+                            }
+                        } else {
+                            self.outbox.send(Notify::Stop).unwrap();
+                            return;
+                        }
                     }
                 };
-
-                self.run_spec(spec.as_ref(), 0);
             }
         })
     }
@@ -176,13 +223,17 @@ impl Workers {
         start_port: u16,
     ) -> Self {
         let start_port = Arc::new(AtomicU16::new(start_port));
+
+        let sequencial_tasks = Arc::new(Mutex::new(Vec::new()));
         let workers: Vec<_> = (0..count)
             .map({
                 let tasks = Arc::clone(&tasks);
+                let sequencial_tasks = Arc::clone(&sequencial_tasks);
                 move |_| {
                     let (command_tx, command_rx) = unbounded();
                     let worker = Worker::new(
                         Arc::clone(&tasks),
+                        Arc::clone(&sequencial_tasks),
                         command_rx,
                         outbox.clone(),
                         Arc::clone(&start_port),
@@ -200,6 +251,8 @@ impl Workers {
 
     /// start all workers
     pub fn start(&mut self) {
+        self.workers.first_mut().unwrap().1.sequencial_worker = true;
+
         let mut join_handles = Vec::new();
         for w in self.workers.iter_mut() {
             let h = w.1.clone().start();
@@ -208,6 +261,20 @@ impl Workers {
         self.join_handles.replace(join_handles);
     }
 
+    pub fn start_sequencial(&mut self) {
+        if let Err(err) = self
+            .workers
+            .first()
+            .unwrap()
+            .0
+            .send(Command::StartSequencial)
+        {
+            error!("start sequencial worker failed, error: {}", err);
+        } else {
+            info!("start sequencial worker success")
+        }
+    }
+
     /// shutdown all workers, must call join_all after this.
     pub fn shutdown(&mut self) {
         if self.is_shutdown {