The reason of why the vertical axis wind turbine (VAWT) is always with low efficiency was analysed and moreover a new type of VAWT with guiding impeller was proposed.The computational fluid dynamics technique was introduced to investigate its aerodynamic performance.The results indicate that the guiding impeller can not only keep the rotor away from the direct impact of coming flow on its suction section,resulting in drag torque,but also improve the effective impact of coming flow on the pressure section of the rotor,both of which contribute to the enhancement of driving torque.So this type of VAWT can smooth away the defects of traditional VAWT and hopefully improve its efficiency.