diff --git a/internal/controller/l1watcher/l1_contracts.go b/internal/controller/l1watcher/l1_contracts.go
index ca489f8..17d26ad 100644
--- a/internal/controller/l1watcher/l1_contracts.go
+++ b/internal/controller/l1watcher/l1_contracts.go
@@ -2,6 +2,8 @@ package l1watcher
 
 import (
 	"context"
+	"crypto/rand"
+	"math/big"
 
 	"github.com/scroll-tech/go-ethereum/common"
 	"github.com/scroll-tech/go-ethereum/ethclient"
@@ -132,9 +134,11 @@ func (l1 *l1Contracts) ParseL1Events(ctx context.Context, db *gorm.DB, start, en
 		l1.tx.Rollback()
 		return 0, err
 	}
+	// About half of results is in [start, end] range.
+	ignore, _ := rand.Int(rand.Reader, big.NewInt(0).SetUint64((end-start+1)*2))
 
 	// store l1chain gateway events.
-	if err = l1.storeGatewayEvents(); err != nil {
+	if err = l1.storeGatewayEvents(ignore.Uint64()); err != nil {
 		l1.tx.Rollback()
 		return 0, err
 	}
diff --git a/internal/controller/l1watcher/l1_gateway.go b/internal/controller/l1watcher/l1_gateway.go
index 9d789aa..3f54d1f 100644
--- a/internal/controller/l1watcher/l1_gateway.go
+++ b/internal/controller/l1watcher/l1_gateway.go
@@ -71,10 +71,14 @@ func (l1 *l1Contracts) registerGatewayHandlers() {
 	})
 }
 
-func (l1 *l1Contracts) storeGatewayEvents() error {
+func (l1 *l1Contracts) storeGatewayEvents(ignore uint64) error {
 	// store l1 eth events.
 	for i := 0; i < len(l1.ethEvents); i++ {
 		event := l1.ethEvents[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l1.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
@@ -88,6 +92,10 @@ func (l1 *l1Contracts) storeGatewayEvents() error {
 	// store l1 erc20 events.
 	for i := 0; i < len(l1.erc20Events); i++ {
 		event := l1.erc20Events[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l1.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
@@ -101,6 +109,10 @@ func (l1 *l1Contracts) storeGatewayEvents() error {
 	// store l1 err721 events.
 	for i := 0; i < len(l1.erc721Events); i++ {
 		event := l1.erc721Events[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l1.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
@@ -114,6 +126,10 @@ func (l1 *l1Contracts) storeGatewayEvents() error {
 	// store l1 erc1155 events.
 	for i := 0; i < len(l1.erc1155Events); i++ {
 		event := l1.erc1155Events[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l1.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
diff --git a/internal/controller/l2watcher/l2_contracts.go b/internal/controller/l2watcher/l2_contracts.go
index 15163c0..0a242f5 100644
--- a/internal/controller/l2watcher/l2_contracts.go
+++ b/internal/controller/l2watcher/l2_contracts.go
@@ -2,13 +2,14 @@ package l2watcher
 
 import (
 	"context"
+	"crypto/rand"
 	"fmt"
-	"math/big"
 
 	"github.com/scroll-tech/go-ethereum/common"
 	"github.com/scroll-tech/go-ethereum/ethclient"
 	"github.com/scroll-tech/go-ethereum/rpc"
 	"gorm.io/gorm"
+	"math/big"
 
 	"chain-monitor/bytecode"
 	"chain-monitor/bytecode/scroll/L2"
@@ -170,15 +171,17 @@ func (l2 *l2Contracts) ParseL2Events(ctx context.Context, db *gorm.DB, start, en
 		l2.tx.Rollback()
 		return 0, err
 	}
+	// About half of results is in [start, end] range.
+	ignore, _ := rand.Int(rand.Reader, big.NewInt(0).SetUint64((end-start+1)*2))
 
 	// store l2Messenger sentMessenger events.
-	if err = l2.storeMessengerEvents(ctx, start, end); err != nil {
+	if err = l2.storeMessengerEvents(ctx, start, end, ignore.Uint64()); err != nil {
 		l2.tx.Rollback()
 		return 0, err
 	}
 
 	// store l2chain gateway events.
-	if err = l2.storeGatewayEvents(); err != nil {
+	if err = l2.storeGatewayEvents(ignore.Uint64()); err != nil {
 		l2.tx.Rollback()
 		return 0, err
 	}
diff --git a/internal/controller/l2watcher/l2_gateway.go b/internal/controller/l2watcher/l2_gateway.go
index d2ce42c..4bd903b 100644
--- a/internal/controller/l2watcher/l2_gateway.go
+++ b/internal/controller/l2watcher/l2_gateway.go
@@ -72,10 +72,14 @@ func (l2 *l2Contracts) registerGatewayHandlers() {
 	})
 }
 
-func (l2 *l2Contracts) storeGatewayEvents() error {
+func (l2 *l2Contracts) storeGatewayEvents(ignore uint64) error {
 	// store l2 eth events.
 	for i := 0; i < len(l2.ethEvents); i++ {
 		event := l2.ethEvents[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l2.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
@@ -89,6 +93,10 @@ func (l2 *l2Contracts) storeGatewayEvents() error {
 	// store l2 erc20 events.
 	for i := 0; i < len(l2.erc20Events); i++ {
 		event := l2.erc20Events[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l2.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
@@ -102,6 +110,10 @@ func (l2 *l2Contracts) storeGatewayEvents() error {
 	// store l2 err721 events.
 	for i := 0; i < len(l2.erc721Events); i++ {
 		event := l2.erc721Events[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l2.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
@@ -115,6 +127,10 @@ func (l2 *l2Contracts) storeGatewayEvents() error {
 	// store l2 erc1155 events.
 	for i := 0; i < len(l2.erc1155Events); i++ {
 		event := l2.erc1155Events[i]
+		// The event should be ignored for test if event number equal to ignore.
+		if event.Number == ignore {
+			continue
+		}
 		if msgHash, exist := l2.txHashMsgHash[event.TxHash]; exist {
 			event.MsgHash = msgHash.String()
 		}
diff --git a/internal/controller/l2watcher/l2_messenger.go b/internal/controller/l2watcher/l2_messenger.go
index be60005..459f9ac 100644
--- a/internal/controller/l2watcher/l2_messenger.go
+++ b/internal/controller/l2watcher/l2_messenger.go
@@ -36,7 +36,7 @@ func (l2 *l2Contracts) registerMessengerHandlers() {
 	})
 }
 
-func (l2 *l2Contracts) storeMessengerEvents(ctx context.Context, start, end uint64) error {
+func (l2 *l2Contracts) storeMessengerEvents(ctx context.Context, start, end, ignore uint64) error {
 	if len(l2.msgSentEvents) == 0 {
 		return nil
 	}
@@ -54,14 +54,17 @@ func (l2 *l2Contracts) storeMessengerEvents(ctx context.Context, start, end uint
 			})
 			continue
 		}
-		msgs := l2.msgSentEvents[number]
-		for i, msg := range msgs {
-			proofs := l2.withdraw.AppendMessages([]common.Hash{common.HexToHash(msg.MsgHash)})
-			// Store the latest one for every block.
-			if i == len(msgs)-1 {
-				msg.MsgProof = common.Bytes2Hex(proofs[0])
+		// If the number equal to ignore number, don't update withdraw root.
+		if number != ignore {
+			msgs := l2.msgSentEvents[number]
+			for i, msg := range msgs {
+				proofs := l2.withdraw.AppendMessages([]common.Hash{common.HexToHash(msg.MsgHash)})
+				// Store the latest one for every block.
+				if i == len(msgs)-1 {
+					msg.MsgProof = common.Bytes2Hex(proofs[0])
+				}
+				msgSentEvents = append(msgSentEvents, msgs[i])
 			}
-			msgSentEvents = append(msgSentEvents, msgs[i])
 		}
 		chainMonitors = append(chainMonitors, &orm.L2ChainConfirm{
 			Number:       number,