diff --git a/src/client/src/client.rs b/src/client/src/client.rs
index c5457e58741f..2055d40b5e0c 100644
--- a/src/client/src/client.rs
+++ b/src/client/src/client.rs
@@ -139,11 +139,11 @@ impl Client {
     }
 
     fn max_grpc_recv_message_size(&self) -> usize {
-        self.inner.channel_manager.config().max_recv_message_size
+        self.inner.channel_manager.config().max_recv_message_size.as_bytes() as usize
     }
 
     fn max_grpc_send_message_size(&self) -> usize {
-        self.inner.channel_manager.config().max_send_message_size
+        self.inner.channel_manager.config().max_send_message_size.as_bytes() as usize
     }
 
     pub(crate) fn make_flight_client(&self) -> Result<FlightClient> {
diff --git a/src/common/grpc/src/channel_manager.rs b/src/common/grpc/src/channel_manager.rs
index d1e372b677c9..98451f13eee7 100644
--- a/src/common/grpc/src/channel_manager.rs
+++ b/src/common/grpc/src/channel_manager.rs
@@ -16,6 +16,7 @@ use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
 use std::sync::Arc;
 use std::time::Duration;
 
+use common_base::readable_size::ReadableSize;
 use common_telemetry::info;
 use dashmap::mapref::entry::Entry;
 use dashmap::DashMap;
@@ -31,8 +32,8 @@ use crate::error::{CreateChannelSnafu, InvalidConfigFilePathSnafu, InvalidTlsCon
 const RECYCLE_CHANNEL_INTERVAL_SECS: u64 = 60;
 pub const DEFAULT_GRPC_REQUEST_TIMEOUT_SECS: u64 = 10;
 pub const DEFAULT_GRPC_CONNECT_TIMEOUT_SECS: u64 = 1;
-pub const DEFAULT_MAX_GRPC_RECV_MESSAGE_SIZE: usize = 512 * 1024 * 1024;
-pub const DEFAULT_MAX_GRPC_SEND_MESSAGE_SIZE: usize = 512 * 1024 * 1024;
+pub const DEFAULT_MAX_GRPC_RECV_MESSAGE_SIZE: ReadableSize = ReadableSize::mb(512);
+pub const DEFAULT_MAX_GRPC_SEND_MESSAGE_SIZE: ReadableSize = ReadableSize::mb(512);
 
 lazy_static! {
     static ref ID: AtomicU64 = AtomicU64::new(0);
@@ -250,9 +251,9 @@ pub struct ChannelConfig {
     pub tcp_nodelay: bool,
     pub client_tls: Option<ClientTlsOption>,
     // Max gRPC receiving(decoding) message size
-    pub max_recv_message_size: usize,
+    pub max_recv_message_size: ReadableSize,
     // Max gRPC sending(encoding) message size
-    pub max_send_message_size: usize,
+    pub max_send_message_size: ReadableSize,
 }
 
 impl Default for ChannelConfig {
diff --git a/src/datanode/src/config.rs b/src/datanode/src/config.rs
index 74c86c5ced53..0b1da56c89a9 100644
--- a/src/datanode/src/config.rs
+++ b/src/datanode/src/config.rs
@@ -328,9 +328,9 @@ pub struct DatanodeOptions {
     pub rpc_hostname: Option<String>,
     pub rpc_runtime_size: usize,
     // Max gRPC receiving(decoding) message size
-    pub rpc_max_recv_message_size: usize,
+    pub rpc_max_recv_message_size: ReadableSize,
     // Max gRPC sending(encoding) message size
-    pub rpc_max_send_message_size: usize,
+    pub rpc_max_send_message_size: ReadableSize,
     pub heartbeat: HeartbeatOptions,
     pub http: HttpOptions,
     pub meta_client: Option<MetaClientOptions>,
diff --git a/src/datanode/src/server.rs b/src/datanode/src/server.rs
index 1847dc4c992a..ad198af81350 100644
--- a/src/datanode/src/server.rs
+++ b/src/datanode/src/server.rs
@@ -40,8 +40,8 @@ impl Services {
         let region_server_handler = Some(Arc::new(region_server.clone()) as _);
         let runtime = region_server.runtime();
         let grpc_config = GrpcServerConfig {
-            max_recv_message_size: opts.rpc_max_recv_message_size,
-            max_send_message_size: opts.rpc_max_send_message_size,
+            max_recv_message_size: opts.rpc_max_recv_message_size.as_bytes() as usize,
+            max_send_message_size: opts.rpc_max_send_message_size.as_bytes() as usize,
         };
 
         Ok(Self {
diff --git a/src/frontend/src/service_config/grpc.rs b/src/frontend/src/service_config/grpc.rs
index e38d6e2a74d1..899a22d3ebf3 100644
--- a/src/frontend/src/service_config/grpc.rs
+++ b/src/frontend/src/service_config/grpc.rs
@@ -33,8 +33,8 @@ impl Default for GrpcOptions {
         Self {
             addr: "127.0.0.1:4001".to_string(),
             runtime_size: 8,
-            max_recv_message_size: ReadableSize(DEFAULT_MAX_GRPC_RECV_MESSAGE_SIZE as u64),
-            max_send_message_size: ReadableSize(DEFAULT_MAX_GRPC_SEND_MESSAGE_SIZE as u64),
+            max_recv_message_size: DEFAULT_MAX_GRPC_RECV_MESSAGE_SIZE,
+            max_send_message_size: DEFAULT_MAX_GRPC_SEND_MESSAGE_SIZE,
         }
     }
 }
diff --git a/src/servers/src/grpc.rs b/src/servers/src/grpc.rs
index 69ea1943a6fa..f87fd7737dca 100644
--- a/src/servers/src/grpc.rs
+++ b/src/servers/src/grpc.rs
@@ -93,8 +93,8 @@ pub struct GrpcServerConfig {
 impl Default for GrpcServerConfig {
     fn default() -> Self {
         Self {
-            max_recv_message_size: DEFAULT_MAX_GRPC_RECV_MESSAGE_SIZE,
-            max_send_message_size: DEFAULT_MAX_GRPC_SEND_MESSAGE_SIZE,
+            max_recv_message_size: DEFAULT_MAX_GRPC_RECV_MESSAGE_SIZE.as_bytes() as usize,
+            max_send_message_size: DEFAULT_MAX_GRPC_SEND_MESSAGE_SIZE.as_bytes() as usize,
         }
     }
 }