The blade dynamic stall behavior of a vertical axis wind turbine with high height to radius ratio was studied using a numerical method. The numerical modeling technique reliability was validated through a comparison of the computational results with the wind tunnel measurement. Below constant wind condition 8m/s, combined with the velocity vector and vorticity contours, the dynamic stall behavior and the rotor power performance were investigated with different tip speed ratios and variant turbine configurations. Illustrated by the simulation, lowering the tip speed ratio and increasing the rotor cord to radius ratio and the blade number will enhance the vortex generation and the flow separation on blades, leading to significant degradation of turbine performance. It can be concluded from the numerical analysis, a vertical axis wind turbine with high height to radius ratio applied in urban area will experience a better performance when operating in the optimal tip speed ratio, with rotor cord to radius ratio between 0.2 and 0.4, and 3 or 4 blades.