diff --git a/contracts/DODOToken/DODOCirculationHelper.sol b/contracts/DODOToken/DODOCirculationHelper.sol
index 05dcd29..0c66fb1 100644
--- a/contracts/DODOToken/DODOCirculationHelper.sol
+++ b/contracts/DODOToken/DODOCirculationHelper.sol
@@ -1,4 +1,4 @@
-    /*
+/*
 
     Copyright 2020 DODO ZOO.
     SPDX-License-Identifier: Apache-2.0
@@ -10,10 +10,7 @@ pragma experimental ABIEncoderV2;
 import {IERC20} from "../intf/IERC20.sol";
 import {SafeMath} from "../lib/SafeMath.sol";
 import {DecimalMath} from "../lib/DecimalMath.sol";
-import {InitializableOwnable} from "../lib/InitializableOwnable.sol";
-import {SafeERC20} from "../lib/SafeERC20.sol";
-import {ReentrancyGuard} from "../lib/ReentrancyGuard.sol";
-import {IDODOApproveProxy} from "../SmartRoute/DODOApproveProxy.sol";
+import {Ownable} from "../lib/Ownable.sol";
 
 interface IDODOCirculationHelper {
     // vDODO 锁仓不算流通
@@ -30,16 +27,30 @@ contract DODOCirculationHelper is Ownable {
     address immutable _DODO_TOKEN_;
     address[] _LOCKED_CONTRACT_ADDRESS_;
 
-            uint256 public _MIN_PENALTY_RATIO_ = 5 * 10**16; // 5%
+    uint256 public _MIN_PENALTY_RATIO_ = 5 * 10**16; // 5%
     uint256 public _MAX_PENALTY_RATIO_ = 15 * 10**16; // 15%
 
- // ============= Helper and calculation function ===============
-    function getVDODOWithdrawFeeRatio() internal returns (uint256) {
-        uint256 dodoCirculationAmout =
-            IDODOCirculationHelper(_DODO_CIRCULATION_HELPER_).getCirculation();
-        // (x - 1)^2 / 81 + (y - 15)^2 / 100 = 1 ==> y = sqrt(100* (x*x +2x ) / 81)) +15
+    constructor(address dodoToken) public {
+        _DODO_TOKEN_ = dodoToken;
+    } // todo
+
+    function addLockedContractAddress(address lockedContract) external onlyOwner {} // todo
+
+    function removeLockedContractAddress(address lockedContract) external onlyOwner {} // todo
+
+    function getCirculation() public view returns (uint256 circulation) {
+        circulation = 10**9;
+        for (uint256 i = 0; i < _LOCKED_CONTRACT_ADDRESS_.length; i++) {
+            circulation -= IERC20(_DODO_TOKEN_).balanceOf(_LOCKED_CONTRACT_ADDRESS_[i]);
+        }
+    }
+
+    function getVDODOWithdrawFeeRatio() external view returns (uint256 ratio) {
+        uint256 dodoCirculationAmout = getCirculation();
+        // (x - 1)^2 / 81 + (y - 15)^2 / 100 = 1
         // y = 5% (x ≤ 1)
         // y = 15% (x ≥ 10)
+        // y = 15% - 10% * sqrt(1-[(x-1)/9]^2)
         uint256 x =
             DecimalMath.divCeil(
                 dodoCirculationAmout,
@@ -51,16 +62,11 @@ contract DODOCirculationHelper is Ownable {
         } else if (x >= 10**19) {
             return _MAX_PENALTY_RATIO_;
         } else {
-            uint256 xSubOne = x.sub(DecimalMath.ONE);
-            xSubOne.sub(9)
-            uint256 rewardAmount =
-                uint256(81 * 10**18).sub(xSubOne.mul(xSubOne)).mul(100).div(81).sqrt().add(15);
-            return rewardAmount;
+            uint256 xTemp = x.sub(DecimalMath.ONE).div(9);
+            uint256 premium = DecimalMath.ONE2.sub(xTemp.mul(xTemp)).sqrt();
+            ratio =
+                _MAX_PENALTY_RATIO_ -
+                DecimalMath.mulFloor(_MAX_PENALTY_RATIO_ - _MIN_PENALTY_RATIO_, premium);
         }
     }
-
-
-
 }
-    
-   
\ No newline at end of file