Abstract: When using ampere-hour integration method to estimate the state of charge（SOC） of vanadium redox flow battery（VRB）,the estimation error often increases because of accumulative error.This paper,based on the first-order RC equivalent circuit model,uses unscented kalman filter method to correct the result of ampere-hour integration method for improving the accuracy of SOC estimation.In addition,the UKF method can estimate the internal resistance of the battery model accurately in real time after converging,which can be used to characterize the state of health（SOH）,so the UKF method can be used to evaluate the SOH of the battery according to the estimation of internal resistance.The charge-discharge experiments were carried out under the setting condition.The experimental results show that the UKF method can not only complete the accurate estimation of the SOC quickly with absolute error less than 2%,but also estimate the internal resistance of the battery accurately,which providing a reference for the determination of SOH.