diff --git a/pkg/controller/subnet.go b/pkg/controller/subnet.go
index eb398d0f06f..3a4da221570 100644
--- a/pkg/controller/subnet.go
+++ b/pkg/controller/subnet.go
@@ -598,7 +598,23 @@ func (c *Controller) checkSubnetConflict(subnet *kubeovnv1.Subnet) error {
 func (c *Controller) updateSubnetDHCPOption(subnet *kubeovnv1.Subnet, needRouter bool) error {
 	var dhcpOptionsUUIDs *ovs.DHCPOptionsUUIDs
 	var err error
-	dhcpOptionsUUIDs, err = c.ovnLegacyClient.UpdateDHCPOptions(subnet.Name, subnet.Spec.CIDRBlock, subnet.Spec.Gateway, subnet.Spec.DHCPv4Options, subnet.Spec.DHCPv6Options, subnet.Spec.EnableDHCP)
+	var mtu int
+	if subnet.Spec.Vlan != "" {
+		mtu = 1500
+	} else {
+		switch c.config.NetworkType {
+		case util.NetworkTypeVxlan:
+			mtu = 1500 - util.VxlanHeaderLength
+		case util.NetworkTypeGeneve:
+			mtu = 1500 - util.GeneveHeaderLength
+		case util.NetworkTypeStt:
+			mtu = 1500 - util.SttHeaderLength
+		default:
+			return fmt.Errorf("invalid network type: %s", c.config.NetworkType)
+		}
+	}
+
+	dhcpOptionsUUIDs, err = c.ovnLegacyClient.UpdateDHCPOptions(subnet.Name, subnet.Spec.CIDRBlock, subnet.Spec.Gateway, subnet.Spec.DHCPv4Options, subnet.Spec.DHCPv6Options, subnet.Spec.EnableDHCP, mtu)
 	if err != nil {
 		klog.Errorf("failed to update dhcp options for switch %s, %v", subnet.Name, err)
 		return err
diff --git a/pkg/ovs/ovn-nbctl-legacy.go b/pkg/ovs/ovn-nbctl-legacy.go
index 00d50140f7d..e310314fb5b 100644
--- a/pkg/ovs/ovn-nbctl-legacy.go
+++ b/pkg/ovs/ovn-nbctl-legacy.go
@@ -413,7 +413,7 @@ func (c *LegacyClient) createDHCPOptions(ls, cidr, optionsStr string) (dhcpOptio
 	return dhcpOptionsUuid, nil
 }
 
-func (c *LegacyClient) updateDHCPv4Options(ls, v4CIDR, v4Gateway, dhcpV4OptionsStr string) (dhcpV4OptionsUuid string, err error) {
+func (c *LegacyClient) updateDHCPv4Options(ls, v4CIDR, v4Gateway, dhcpV4OptionsStr string, mtu int) (dhcpV4OptionsUuid string, err error) {
 	dhcpV4OptionsStr = strings.ReplaceAll(dhcpV4OptionsStr, " ", "")
 	dhcpV4Options, err := c.ListDHCPOptions(true, ls, kubeovnv1.ProtocolIPv4)
 	if err != nil {
@@ -427,7 +427,7 @@ func (c *LegacyClient) updateDHCPv4Options(ls, v4CIDR, v4Gateway, dhcpV4OptionsS
 			mac := util.GenerateMac()
 			if len(dhcpV4OptionsStr) == 0 {
 				// default dhcp v4 options
-				dhcpV4OptionsStr = fmt.Sprintf("lease_time=%d,router=%s,server_id=%s,server_mac=%s", 3600, v4Gateway, "169.254.0.254", mac)
+				dhcpV4OptionsStr = fmt.Sprintf("lease_time=%d,router=%s,server_id=%s,server_mac=%s,mtu=%d", 3600, v4Gateway, "169.254.0.254", mac, mtu)
 			}
 			dhcpV4OptionsUuid, err = c.createDHCPOptions(ls, v4CIDR, dhcpV4OptionsStr)
 			if err != nil {
@@ -442,7 +442,7 @@ func (c *LegacyClient) updateDHCPv4Options(ls, v4CIDR, v4Gateway, dhcpV4OptionsS
 				if len(mac) == 0 {
 					mac = util.GenerateMac()
 				}
-				dhcpV4OptionsStr = fmt.Sprintf("lease_time=%d,router=%s,server_id=%s,server_mac=%s", 3600, v4Gateway, "169.254.0.254", mac)
+				dhcpV4OptionsStr = fmt.Sprintf("lease_time=%d,router=%s,server_id=%s,server_mac=%s,mtu=%d", 3600, v4Gateway, "169.254.0.254", mac, mtu)
 			}
 			_, err = c.ovnNbCommand("set", "dhcp_options", v4Options.UUID, fmt.Sprintf("cidr=%s", v4CIDR),
 				fmt.Sprintf("options=%s", strings.ReplaceAll(dhcpV4OptionsStr, ":", "\\:")))
@@ -512,7 +512,7 @@ func (c *LegacyClient) updateDHCPv6Options(ls, v6CIDR, dhcpV6OptionsStr string)
 	return
 }
 
-func (c *LegacyClient) UpdateDHCPOptions(ls, cidrBlock, gateway, dhcpV4OptionsStr, dhcpV6OptionsStr string, enableDHCP bool) (dhcpOptionsUUIDs *DHCPOptionsUUIDs, err error) {
+func (c *LegacyClient) UpdateDHCPOptions(ls, cidrBlock, gateway, dhcpV4OptionsStr, dhcpV6OptionsStr string, enableDHCP bool, mtu int) (dhcpOptionsUUIDs *DHCPOptionsUUIDs, err error) {
 	dhcpOptionsUUIDs = &DHCPOptionsUUIDs{}
 	if enableDHCP {
 		var v4CIDR, v6CIDR string
@@ -530,7 +530,7 @@ func (c *LegacyClient) UpdateDHCPOptions(ls, cidrBlock, gateway, dhcpV4OptionsSt
 			v4Gateway = gateways[0]
 		}
 
-		dhcpOptionsUUIDs.DHCPv4OptionsUUID, err = c.updateDHCPv4Options(ls, v4CIDR, v4Gateway, dhcpV4OptionsStr)
+		dhcpOptionsUUIDs.DHCPv4OptionsUUID, err = c.updateDHCPv4Options(ls, v4CIDR, v4Gateway, dhcpV4OptionsStr, mtu)
 		if err != nil {
 			klog.Errorf("update dhcp options for switch %s failed: %v", ls, err)
 			return nil, err