The world is short of energy,tidal current energy has been a hot topic in many countries because of its superiority. In this paper,a new type of impeller was designed to solve the problem that the current tidal current turbine couldn’t catch energy in both directions. The basic airfoil NACA24112 was calculated by the airfoil analysis software Xfoil and simulation software Fluent and used to design a new “S”airfoil,The chord length and twist angle of each blade section were calculated according to Wilson method,finally used CATIA for 3 d modeling and Fluent for simulating the model. A bidirectional fairing was designed to improve power generation,and its best flaring angle was 26° by Fluent simulation analysis. Through the flume experiment,the results show the impeller has good bidirectional characteristic and has low start velocity thanks to the effect of fairing,and can reach the maximum generation efficiency about 25. 4% at 2 m/s.