Recently, wind energy has been used as one of the renewable energies to replace fossil fuels. Wind turbines can be classified in terms of two types, based on the direction of the axis of rotation: that is, a vertical-axis wind turbine and a horizontal-axis wind turbine. The operating principle of a wind turbine can be classified in terms of two types: lift-type wind turbines and drag-type wind turbines. In this study, we focus on the lift-type wind turbine with a vertical axis that does not depend on the direction of the wind. We aim to use a small capacity power generation of 20kW or less. The aim of this study is to find the effects on controlled separation over the NACA0025 blade set up with a slatted blade using velocity vectors, streamline and pressure distributions obtained from the numerical simulation.