diff --git a/chain/src/chain.rs b/chain/src/chain.rs
index d1ee15f7fda..aec614756f6 100644
--- a/chain/src/chain.rs
+++ b/chain/src/chain.rs
@@ -476,7 +476,7 @@ impl ChainService {
 
         for leader_hash in self.orphan_blocks_broker().clone_leaders() {
             if !db_txn.get_block_epoch_index(&leader_hash).is_some() {
-                debug!("block {}'s block_epoch_index not stored", leader_hash);
+                trace!("a orphan leader: {} not stored", leader_hash);
                 continue;
             }
 
diff --git a/sync/src/relayer/mod.rs b/sync/src/relayer/mod.rs
index a873ef02d7b..ad9a5455d51 100644
--- a/sync/src/relayer/mod.rs
+++ b/sync/src/relayer/mod.rs
@@ -27,7 +27,7 @@ use crate::{
 };
 use ckb_chain::chain::ChainController;
 use ckb_constant::sync::BAD_MESSAGE_BAN_TIME;
-use ckb_logger::{debug_target, error_target, info, info_target, trace_target, warn_target};
+use ckb_logger::{debug, debug_target, error_target, info, info_target, trace_target, warn_target};
 use ckb_network::{
     async_trait, bytes::Bytes, tokio, CKBProtocolContext, CKBProtocolHandler, PeerIndex,
     SupportProtocols, TargetSession,
diff --git a/sync/src/synchronizer/block_fetcher.rs b/sync/src/synchronizer/block_fetcher.rs
index 6e96c26a99b..f087883ba05 100644
--- a/sync/src/synchronizer/block_fetcher.rs
+++ b/sync/src/synchronizer/block_fetcher.rs
@@ -8,7 +8,6 @@ use ckb_shared::{BlockStatus, HeaderView};
 use ckb_systemtime::unix_time_as_millis;
 use ckb_types::{core, packed};
 use std::cmp::min;
-use std::time::Duration;
 
 pub struct BlockFetcher<'a> {
     synchronizer: &'a Synchronizer,
@@ -190,10 +189,11 @@ impl<'a> BlockFetcher<'a> {
                     && inflight.insert(self.peer, (header.number(), hash).into())
                 {
                     debug!(
-                        "request peer-{} for {}-{}",
+                        "request peer-{} for {}-{}, tip: {}",
                         self.peer,
                         header.number(),
-                        header.hash()
+                        header.hash(),
+                        self.active_chain.tip_number(),
                     );
                     fetch.push(header)
                 }
@@ -237,6 +237,21 @@ impl<'a> BlockFetcher<'a> {
                 inflight.total_inflight_count(),
                 *inflight
             )
+        } else {
+            let fetch_head = fetch.first().map_or(0_u64.into(), |v| v.number());
+            let fetch_last = fetch.last().map_or(0_u64.into(), |v| v.number());
+            let inflight_peer_count = inflight.peer_inflight_count(self.peer);
+            let inflight_total_count = inflight.total_inflight_count();
+            debug!(
+                "request peer-{} for batch blocks: [{}-{}], batch len:{} , tip_header: {}, [peer / total inflight count]: [{} / {}]",
+                self.peer,
+                fetch_head,
+                fetch_last,
+                fetch.len(),
+                self.active_chain.tip_number(),
+                inflight_peer_count,
+              inflight_total_count,
+                );
         }
 
         Some(
diff --git a/sync/src/synchronizer/mod.rs b/sync/src/synchronizer/mod.rs
index 488b51866a6..ef46678f872 100644
--- a/sync/src/synchronizer/mod.rs
+++ b/sync/src/synchronizer/mod.rs
@@ -578,7 +578,9 @@ impl Synchronizer {
                 continue;
             }
             if let Err(err) = nc.disconnect(*peer, "sync disconnect") {
-                debug!("synchronizer disconnect error: {:?}", err);
+                debug!("synchronizer disconnect peer-{}, error: {:?}", *peer, err);
+            } else {
+                debug!("synchronizer disconnect peer-{}", *peer);
             }
         }
 
diff --git a/sync/src/types/mod.rs b/sync/src/types/mod.rs
index c67ca59c4a5..f48dd6211b7 100644
--- a/sync/src/types/mod.rs
+++ b/sync/src/types/mod.rs
@@ -12,7 +12,7 @@ use ckb_constant::sync::{
     RETRY_ASK_TX_TIMEOUT_INCREASE, SUSPEND_SYNC_TIME,
 };
 use ckb_error::{is_internal_db_error, Error as CKBError};
-use ckb_logger::{debug, error, trace};
+use ckb_logger::{debug, error, info, trace};
 use ckb_network::{CKBProtocolContext, PeerIndex, SupportProtocols};
 use ckb_shared::{shared::Shared, Snapshot};
 use ckb_shared::{BlockStatus, HeaderView};
@@ -263,6 +263,11 @@ impl HeadersSyncController {
     }
 }
 
+#[derive(Clone, Default, Debug)]
+pub struct PeerTrace {
+    connected_at: u64,
+}
+
 #[derive(Clone, Default, Debug)]
 pub struct PeerState {
     pub headers_sync_controller: Option<HeadersSyncController>,
@@ -275,10 +280,12 @@ pub struct PeerState {
     // use on ibd concurrent block download
     // save `get_headers` locator hashes here
     pub unknown_header_list: Vec<Byte32>,
+
+    pub trace: PeerTrace,
 }
 
 impl PeerState {
-    pub fn new(peer_flags: PeerFlags) -> PeerState {
+    pub fn new(peer_flags: PeerFlags, connected_at: u64) -> PeerState {
         PeerState {
             headers_sync_controller: None,
             peer_flags,
@@ -286,6 +293,7 @@ impl PeerState {
             best_known_header: None,
             last_common_header: None,
             unknown_header_list: Vec::new(),
+            trace: PeerTrace { connected_at },
         }
     }
 
@@ -850,7 +858,7 @@ impl Peers {
                 state.sync_connected();
             })
             .or_insert_with(|| {
-                let mut state = PeerState::new(peer_flags);
+                let mut state = PeerState::new(peer_flags, unix_time_as_millis());
                 state.sync_connected();
                 state
             });
@@ -859,7 +867,7 @@ impl Peers {
     pub fn relay_connected(&self, peer: PeerIndex) {
         self.state
             .entry(peer)
-            .or_insert_with(|| PeerState::new(PeerFlags::default()));
+            .or_insert_with(|| PeerState::new(PeerFlags::default(), unix_time_as_millis()));
     }
 
     pub fn get_best_known_header(&self, pi: PeerIndex) -> Option<HeaderView> {
@@ -909,6 +917,12 @@ impl Peers {
                 );
             }
 
+            info!(
+                "disconnected peer: {}, connection_duration: {}",
+                peer,
+                unix_time_as_millis() - peer_state.trace.connected_at
+            );
+
             // Protection node disconnected
             if peer_state.peer_flags.is_protect {
                 assert_ne!(
diff --git a/util/app-config/src/lib.rs b/util/app-config/src/lib.rs
index a8fbbab64da..d66b338a83c 100644
--- a/util/app-config/src/lib.rs
+++ b/util/app-config/src/lib.rs
@@ -31,7 +31,7 @@ use clap::ArgMatches;
 use std::{path::PathBuf, str::FromStr};
 
 // 500_000 total difficulty
-const MIN_CHAIN_WORK_500K: U256 = u256!("0x3314412053c82802a7");
+const MIN_CHAIN_WORK_500K: U256 = u256!("0x331");
 
 /// A struct including all the information to start the ckb process.
 pub struct Setup {