In this study, the effect of both overlap ratio of blades and blade angular position on the performance of a savonius vertical axis wind turbine are investigated with computational fluids dynamics method. The computations are conducted for the wind turbine with overlap ratios of 0, 0.1 and 0.2. Also, the blade angular position varies from 0° to 90°. The results show that the optimum values for the power coefficient occurs when the tip speed ratio ranges as 0.75≤λ≤1.15. It is also concluded that the maximum value of the power coefficient and torque coefficient is obtained for overlap ratio of 0.1 for λ=1. The highest peak of the torque coefficient is obtained at the blade angular position of 30° for all overlap ratios. In addition, the maximum value of the power coefficient for overlap ratio of 0.1 and blade angular position of 30° is obtained as 0.2503 when λ = 1 which is 45% more than the blade angular position of 0°.