diff --git a/.travis.yml b/.travis.yml
index 210d4c956e..7fa73dd1b7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,15 +16,15 @@ env:
 
 matrix:
   include:
-    - rust: 1.31.1
+    - rust: 1.32.0
       os: osx
       env: FMT=true CHECK=true TEST=true
       if: type = pull_request
-    - rust: 1.31.1
+    - rust: 1.32.0
       os: osx
       env: FMT=true CHECK=true TEST=true
       if: type != pull_request
-    - rust: 1.31.1
+    - rust: 1.32.0
       os: linux
       env: TEST=true
       if: type != pull_request
diff --git a/README.md b/README.md
index 033bf17b0c..55b3a9a054 100644
--- a/README.md
+++ b/README.md
@@ -32,13 +32,13 @@ The contribution workflow is described in [CONTRIBUTING.md](CONTRIBUTING.md), an
 
 ## Build dependencies
 
-CKB is currently tested mainly with `stable-1.31.1` on Linux and Mac OSX.
+CKB is currently tested mainly with `stable-1.32.0` on Linux and Mac OSX.
 
 We recommend installing Rust through [rustup](https://www.rustup.rs/)
 
 ```bash
 # Get rustup from rustup.rs, then in your `ckb` folder:
-rustup override set 1.31.1
+rustup override set 1.32.0
 rustup component add rustfmt
 rustup component add clippy
 ```
diff --git a/core/src/transaction.rs b/core/src/transaction.rs
index 2b621e0900..88adcf278e 100644
--- a/core/src/transaction.rs
+++ b/core/src/transaction.rs
@@ -4,7 +4,6 @@ use crate::script::Script;
 use crate::BlockNumber;
 pub use crate::Capacity;
 use bincode::{deserialize, serialize};
-use ckb_util::u64_to_bytes;
 use faster_hex::hex_string;
 use hash::sha3_256;
 use numext_fixed_hash::H256;
@@ -73,7 +72,7 @@ impl CellInput {
                 0,
                 Vec::new(),
                 None,
-                Some(u64_to_bytes(block_number.to_le()).to_vec()),
+                Some(block_number.to_le_bytes().to_vec()),
                 Vec::new(),
             ),
         }
diff --git a/docker/hub/Dockerfile b/docker/hub/Dockerfile
index 4041c5ac91..c529997a97 100644
--- a/docker/hub/Dockerfile
+++ b/docker/hub/Dockerfile
@@ -3,7 +3,7 @@ FROM ubuntu:bionic as ckb-builder
 ENV RUSTUP_HOME=/usr/local/rustup \
     CARGO_HOME=/usr/local/cargo \
     PATH=/usr/local/cargo/bin:$PATH \
-    RUST_VERSION=1.31.1
+    RUST_VERSION=1.32.0
 
 RUN set -eux; \
     apt-get update; \
diff --git a/network/src/ckb_protocol.rs b/network/src/ckb_protocol.rs
index 758b974ec5..7567f18470 100644
--- a/network/src/ckb_protocol.rs
+++ b/network/src/ckb_protocol.rs
@@ -115,7 +115,7 @@ where
                             IoErrorKind::Other,
                             format!("faild to upgrade ckb_protocol, error: {}", err),
                         ))
-                    }
+                    };
                 }
             };
 
diff --git a/network/src/ckb_service.rs b/network/src/ckb_service.rs
index bd0d77e753..b0ae15e715 100644
--- a/network/src/ckb_service.rs
+++ b/network/src/ckb_service.rs
@@ -64,7 +64,7 @@ impl CKBService {
                 return Box::new(future::err(IoError::new(
                     IoErrorKind::Other,
                     format!("can't find peer {:?}", peer_id),
-                )))
+                )));
             }
         };
 
diff --git a/protocol/src/lib.rs b/protocol/src/lib.rs
index 2402ef1f19..900a822040 100644
--- a/protocol/src/lib.rs
+++ b/protocol/src/lib.rs
@@ -6,7 +6,6 @@ mod protocol_generated;
 
 pub use crate::protocol_generated::ckb::protocol::*;
 use byteorder::{ByteOrder, LittleEndian, WriteBytesExt};
-use ckb_util::u64_to_bytes;
 use hash::sha3_256;
 use numext_fixed_hash::H256;
 use siphasher::sip::SipHasher;
@@ -57,7 +56,7 @@ pub fn short_transaction_id(key0: u64, key1: u64, transaction_hash: &H256) -> Sh
     hasher.write(transaction_hash.as_bytes());
     let siphash_transaction_hash = hasher.finish();
 
-    let siphash_transaction_hash_bytes = u64_to_bytes(siphash_transaction_hash.to_le());
+    let siphash_transaction_hash_bytes = siphash_transaction_hash.to_le_bytes();
 
     let mut short_transaction_id = [0u8; 6];
 
diff --git a/rust-toolchain b/rust-toolchain
index 6bae540243..359c41089a 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-1.31.1
+1.32.0
diff --git a/src/cli/run_impl.rs b/src/cli/run_impl.rs
index e983fe46ce..9c2150f9cf 100644
--- a/src/cli/run_impl.rs
+++ b/src/cli/run_impl.rs
@@ -21,7 +21,6 @@ use ckb_sync::{
 use crypto::secp::Generator;
 use log::info;
 use numext_fixed_hash::H256;
-use serde_json;
 use std::sync::Arc;
 use std::thread;
 
diff --git a/util/src/lib.rs b/util/src/lib.rs
index 328e76b5ae..2c2f0cac59 100644
--- a/util/src/lib.rs
+++ b/util/src/lib.rs
@@ -1,6 +1,5 @@
 mod unstable;
 
-pub use crate::unstable::int_to_from_bytes::u64_to_bytes;
 pub use parking_lot::{
     Condvar, Mutex, MutexGuard, RwLock, RwLockReadGuard, RwLockUpgradableReadGuard,
     RwLockWriteGuard,
diff --git a/util/src/unstable/int_to_from_bytes.rs b/util/src/unstable/int_to_from_bytes.rs
deleted file mode 100644
index cfaa93c613..0000000000
--- a/util/src/unstable/int_to_from_bytes.rs
+++ /dev/null
@@ -1,19 +0,0 @@
-/// Return the memory representation of this u64 as a byte array.
-///
-/// The target platform’s native endianness is used.
-/// Portable code likely wants to use this with [`to_be`] or [`to_le`].
-///
-/// [`to_be`]: #method.to_be
-/// [`to_le`]: #method.to_le
-///
-/// # Examples
-///
-/// ```
-/// let bytes = ckb_util::u64_to_bytes(1u64.to_le());
-/// assert_eq!(bytes, [1, 0, 0, 0, 0, 0, 0, 0]);
-/// ```
-/// remove it when feature "int_to_from_bytes" stable
-#[inline]
-pub fn u64_to_bytes(input: u64) -> [u8; 8] {
-    unsafe { ::std::mem::transmute(input) }
-}
diff --git a/util/src/unstable/mod.rs b/util/src/unstable/mod.rs
index dd734e9658..8b13789179 100644
--- a/util/src/unstable/mod.rs
+++ b/util/src/unstable/mod.rs
@@ -1 +1 @@
-pub mod int_to_from_bytes;
+