The vertical axis wind turbine (VAWT) has advantages over horizontal axis wind turbine (HAWT) that it allows less chance to be degraded independent of wind direction and turbine can be operated even at the low wind speed. The objective of this study is not only analyze aerodynamics of the VAWT airfoil but also investigate the ideal shape and number of airfoils. TSR effect for appropriate VAWT System is also investigated. As the numerical simulation discloses local physical features around airfoil, aerodynamic performance are computed such as lift, drag and torque. In this study more effective airfoil shape is suggested through vortex-airfoil interaction analysis in VAWT system.