The invention discloses a vertical axis wind turbine with a bending line of a straight-blade airfoil coincident with a wind wheel moving trajectory. The bending line of the blade airfoil is coincident with the wind wheel moving trajectory, and airfoil chord lengths at an upper blade tip and a lower blade tip of each blade are decreased gradually. Each blade is connected with a wind turbine spindle through two support rods, and the blades are parallel to the spindle and capable of rotating round the spindle. Compared with traditional straight blades, the blades of the vertical axis wind turbine have the advantages that torque peak value and utilization rate of wind energy are high, and down-wind pneumatic pushing force is reduced. By application and popularization of the wind turbine, unit electric energy output of the wind turbine is increased beneficially, and service life is prolonged.