diff --git a/contracts/DODOToken/DODOCirculationHelper.sol b/contracts/DODOToken/DODOCirculationHelper.sol
new file mode 100644
index 0000000..05dcd29
--- /dev/null
+++ b/contracts/DODOToken/DODOCirculationHelper.sol
@@ -0,0 +1,66 @@
+    /*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+pragma solidity 0.6.9;
+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";
+
+interface IDODOCirculationHelper {
+    // vDODO 锁仓不算流通
+    function getCirculation() external returns (uint256);
+
+    function getVDODOWithdrawFeeRatio() external returns (uint256);
+}
+
+contract DODOCirculationHelper is Ownable {
+    using SafeMath for uint256;
+
+    // ============ Storage ============
+
+    address immutable _DODO_TOKEN_;
+    address[] _LOCKED_CONTRACT_ADDRESS_;
+
+            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
+        // y = 5% (x ≤ 1)
+        // y = 15% (x ≥ 10)
+        uint256 x =
+            DecimalMath.divCeil(
+                dodoCirculationAmout,
+                IERC20(_DODO_TOKEN_).balanceOf(address(this))
+            );
+
+        if (x <= 10**18) {
+            return _MIN_PENALTY_RATIO_;
+        } 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;
+        }
+    }
+
+
+
+}
+    
+   
\ No newline at end of file
diff --git a/contracts/DODOToken/vDODOToken.sol b/contracts/DODOToken/vDODOToken_Lei.sol
similarity index 100%
rename from contracts/DODOToken/vDODOToken.sol
rename to contracts/DODOToken/vDODOToken_Lei.sol