diff --git a/.github/coverage-config.yaml b/.github/coverage-config.yaml
index 55c7435..425c49b 100644
--- a/.github/coverage-config.yaml
+++ b/.github/coverage-config.yaml
@@ -1,5 +1,6 @@
 exclude:
   # Exclude files or packages matching their paths
   paths:
-    - \.pb\.go$    # excludes all protobuf generated files
-    - ^contracts     # exclude package `contracts`
\ No newline at end of file
+    - \.pb\.go$   # excludes all protobuf generated files
+    - ^contracts  # exclude package `contracts`
+    - fork.go     # exclude file `fork.go`
\ No newline at end of file
diff --git a/README.md b/README.md
index bf89fbc..dde4716 100644
--- a/README.md
+++ b/README.md
@@ -11,12 +11,15 @@
 - [x] Set code for address
 - [x] Start impersonate an address
 - [x] Stop impersonate an address
+- [x] Impersonate a txn(require impersonate account)
 - [ ] Impersonate and make only 1 txn
 - [ ] Write Erc721 balance
 
 ## How to Use:
 ```go
-    forkRpcEndpoint, err := foundryutils.StartFork("https://rpc.ankr.com/eth", nil)
+    // if you want to fork on test code, you can use `StartFork` function
+    // otherwise, you can run anvil separately then call `SetupClient`
+    forkRpcEndpoint, err := foundryutils.StartFork("https://rpc.ankr.com/eth", foundryutils.ForkOpts{})
     if err != nil {
         // do something with err
     }
diff --git a/cheat/cheat.go b/cheat/cheat.go
index f885b47..46038e4 100644
--- a/cheat/cheat.go
+++ b/cheat/cheat.go
@@ -1,6 +1,7 @@
 package cheat
 
 import (
+	"fmt"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -39,3 +40,22 @@ func StartImpersonateAccount(account common.Address) error {
 func StopImpersonateAccount(account common.Address) error {
 	return client.GlobalClient.RpcClient.Call(nil, "anvil_stopImpersonatingAccount", account.Hex())
 }
+
+// make an impersonate txn
+func SendImpersonateTxn(from, to common.Address, gas uint64, value, gasPrice *big.Int, data []byte) error {
+	return client.GlobalClient.RpcClient.Call(nil, "eth_sendTransaction",
+		struct {
+			From     string `json:"from"`
+			To       string `json:"to"`
+			Value    string `json:"value"`
+			Gas      string `json:"gas"`
+			GasPrice string `json:"gasPrice"`
+		}{
+			From:     from.Hex(),
+			To:       to.Hex(),
+			Value:    hexutil.Encode(value.Bytes()),
+			Gas:      fmt.Sprintf("0x%x", gas),
+			GasPrice: hexutil.Encode(gasPrice.Bytes()),
+		},
+	)
+}
diff --git a/cheat/cheat_test.go b/cheat/cheat_test.go
index a87c72a..1a7925d 100644
--- a/cheat/cheat_test.go
+++ b/cheat/cheat_test.go
@@ -2,7 +2,6 @@ package cheat
 
 import (
 	"context"
-	"fmt"
 	"io"
 	"math/big"
 	"os/exec"
@@ -71,23 +70,8 @@ func (s *CheatSuite) TestStartImpersonateAccount() {
 	s.Assert().NoError(
 		StartImpersonateAccount(helper.DummyAccount),
 	)
-	// tx := types.NewTx(0, common.HexToAddress("0x08081999"), big.NewInt(1000000000000000000), 21000, big.NewInt(30000000000), nil)
 	s.Assert().NoError(
-		client.GlobalClient.RpcClient.Call(nil, "eth_sendTransaction",
-			struct {
-				From     string `json:"from"`
-				To       string `json:"to"`
-				Value    string `json:"value"`
-				Gas      string `json:"gas"`
-				GasPrice string `json:"gasPrice"`
-			}{
-				From:     helper.DummyAccount.Hex(),
-				To:       common.HexToAddress("0x08081999").Hex(),
-				Value:    hexutil.Encode(big.NewInt(1000000000000000000).Bytes()),
-				Gas:      fmt.Sprintf("0x%x", 21000),
-				GasPrice: hexutil.Encode(big.NewInt(10000000000000).Bytes()),
-			},
-		),
+		SendImpersonateTxn(helper.DummyAccount, common.HexToAddress("0x08081999"), 21000, big.NewInt(1000000000000000000), big.NewInt(10000000000000), nil),
 	)
 	b, err := client.GlobalClient.EthClient.BalanceAt(context.Background(), common.HexToAddress("0x08081999"), nil)
 	s.Assert().NoError(err)
diff --git a/fork.go b/fork.go
index 607d01e..bc4b704 100644
--- a/fork.go
+++ b/fork.go
@@ -12,37 +12,39 @@ var (
 	mu          sync.Mutex
 )
 
+type ForkOpts struct {
+	Port        string
+	BlockNumber *big.Int
+}
+
 // start fork a network for testing purposes
-func StartFork(forkUrl string, port string, blockNumber *big.Int) (string, error) {
+func StartFork(forkUrl string, opt ForkOpts) (string, error) {
 	_, err := exec.LookPath("anvil")
 	if err != nil {
 		return "", err
 	}
-	if port == "" {
-		port = "8545"
-	}
-	mu.Lock()
 	if forkProcess != nil {
-		forkProcess.Process.Kill()
-		if err := forkProcess.Wait(); err != nil {
-			return "", fmt.Errorf("stop old fork process failed: %v", err.Error())
-		}
+		return "", fmt.Errorf("fork process already exists")
+	}
+	if opt.Port == "" {
+		opt.Port = "8545"
 	}
 	args := []string{
 		"--fork-url", forkUrl,
-		"--port", port,
+		"--port", opt.Port,
 	}
-	if blockNumber != nil {
+	if opt.BlockNumber != nil {
 		args = append(args, []string{
-			"--fork-block-number", blockNumber.String(),
+			"--fork-block-number", opt.BlockNumber.String(),
 		}...)
 	}
-	forkProcess = exec.Command("anvil", args...)
+	mu.Lock()
+	forkProcess = exec.Command("anvil", args...) // #nosec
 	defer mu.Unlock()
 	if err := forkProcess.Start(); err != nil {
 		return "", err
 	}
-	return fmt.Sprintf("http://localhost:%s", port), nil
+	return fmt.Sprintf("http://localhost:%s", opt.Port), nil
 }
 
 // stop current fork process
@@ -50,7 +52,9 @@ func StopFork() error {
 	mu.Lock()
 	defer mu.Unlock()
 	if forkProcess != nil {
-		forkProcess.Process.Kill()
+		if err := forkProcess.Process.Kill(); err != nil {
+			return fmt.Errorf("kill old fork process failed: %v", err.Error())
+		}
 		if err := forkProcess.Wait(); err != nil {
 			return fmt.Errorf("stop old fork process failed: %v", err.Error())
 		}