diff --git a/contracts/impl/Admin.sol b/contracts/impl/Admin.sol
index 9e0a7a1..fd89052 100644
--- a/contracts/impl/Admin.sol
+++ b/contracts/impl/Admin.sol
@@ -19,7 +19,16 @@ import {Storage} from "./Storage.sol";
 contract Admin is Storage {
     // ============ Events ============
 
-    event UpdateGasPriceLimit(uint256 newGasPriceLimit);
+    event UpdateGasPriceLimit(uint256 oldGasPriceLimit, uint256 newGasPriceLimit);
+
+    event UpdateLiquidityProviderFeeRate(
+        uint256 oldLiquidityProviderFeeRate,
+        uint256 newLiquidityProviderFeeRate
+    );
+
+    event UpdateMaintainerFeeRate(uint256 oldMaintainerFeeRate, uint256 newMaintainerFeeRate);
+
+    event UpdateK(uint256 oldK, uint256 newK);
 
     // ============ Params Setting Functions ============
 
@@ -36,23 +45,26 @@ contract Admin is Storage {
     }
 
     function setLiquidityProviderFeeRate(uint256 newLiquidityPorviderFeeRate) external onlyOwner {
+        emit UpdateLiquidityProviderFeeRate(_LP_FEE_RATE_, newLiquidityPorviderFeeRate);
         _LP_FEE_RATE_ = newLiquidityPorviderFeeRate;
         _checkDODOParameters();
     }
 
     function setMaintainerFeeRate(uint256 newMaintainerFeeRate) external onlyOwner {
+        emit UpdateMaintainerFeeRate(_MT_FEE_RATE_, newMaintainerFeeRate);
         _MT_FEE_RATE_ = newMaintainerFeeRate;
         _checkDODOParameters();
     }
 
     function setK(uint256 newK) external onlyOwner {
+        emit UpdateK(_K_, newK);
         _K_ = newK;
         _checkDODOParameters();
     }
 
     function setGasPriceLimit(uint256 newGasPriceLimit) external onlySupervisorOrOwner {
+        emit UpdateGasPriceLimit(_GAS_PRICE_LIMIT_, newGasPriceLimit);
         _GAS_PRICE_LIMIT_ = newGasPriceLimit;
-        emit UpdateGasPriceLimit(newGasPriceLimit);
     }
 
     // ============ System Control Functions ============
diff --git a/contracts/impl/Trader.sol b/contracts/impl/Trader.sol
index 65b3060..ecb8c1e 100644
--- a/contracts/impl/Trader.sol
+++ b/contracts/impl/Trader.sol
@@ -30,7 +30,9 @@ contract Trader is Storage, Pricing, Settlement {
 
     event BuyBaseToken(address indexed buyer, uint256 receiveBase, uint256 payQuote);
 
-    event MaintainerFee(bool isBaseToken, uint256 amount);
+    event ChargeMaintainerFeeBase(address indexed maintainer, uint256 amount);
+
+    event ChargeMaintainerFeeQuote(address indexed maintainer, uint256 amount);
 
     // ============ Modifiers ============
 
@@ -82,7 +84,9 @@ contract Trader is Storage, Pricing, Settlement {
 
         _donateQuoteToken(lpFeeQuote);
         emit SellBaseToken(msg.sender, amount, receiveQuote);
-        emit MaintainerFee(false, mtFeeQuote);
+        if (mtFeeQuote != 0) {
+            emit ChargeMaintainerFeeQuote(_MAINTAINER_, mtFeeQuote);
+        }
 
         return receiveQuote;
     }
@@ -123,7 +127,9 @@ contract Trader is Storage, Pricing, Settlement {
 
         _donateBaseToken(lpFeeBase);
         emit BuyBaseToken(msg.sender, amount, payQuote);
-        emit MaintainerFee(true, mtFeeBase);
+        if (mtFeeBase != 0) {
+            emit ChargeMaintainerFeeBase(_MAINTAINER_, mtFeeBase);
+        }
 
         return payQuote;
     }