This paper presents the performance characteristics of Darrieus-type vertical axis wind turbine(VAWT) with NACA airfoil blades. The blades are considered various chord length, twist angles and pitch angles. A number of numerical simulations have been made to predict the power and torque of the VAWT. For the numerical simulation of VAWT, the unsteady RANS (Reynolds-Averaged Navier-Stokes) equation is used to analyze the flow, torque and power acting on the blade. The twist angle, one of key parameters in the VAWT design, is chosen and changed with 0°, 10°, 20°, and 30°. The ratio of rotor height (H) and diameter (D) is set to be 0.75. The numerical results include the variation of torque and power coefficient against the TSR(Tip Speed Ratio) and pitch angle.