In order to improve the performance of vertical axis wind turbine, the variable pitch vertical axis wind turbine (VAWT) was studied. The optimum pitch angles at different azimuth angles were calculated by the blade element theory to maximize the drive moment of blade at any position. After doing dynamic regional UDF (user-defined function) approach on sliding mesh, dynamic mesh and a combination of both, the diverse numerical simulation methods of active control for variable pitch vertical axis wind turbine were built. Finally, the total torque generated as well as the power coefficient were obtained. The reliability of numerical simulation was verified by comparative analysis between the experimental and simulation results about VAWT. The results indicated that the power coefficient of vertical axis wind turbine was improved by the method of variable pitch, especially in the case of low tip speed ratios (TSR), where the capability of self-starting was improved greatly. Compared with the fixed-pitch vertical axis wind turbine, the power was increased by about 90% at the tip speed ratio of 1.5, 2.0 and 2.5.