The invention provides a perpendicular shaft wind turbine with an adjustable windward area. The perpendicular shaft wind turbine comprises a main shaft and blades and further comprises a scissor fork type mechanism, sliding rails, a rope wheel, a servo taking-up and paying-off motor and ropes, the servo taking-up and paying-off motor is coaxially installed at the top of the main shaft, the scissor fork type mechanism is installed on the main shaft, the rope wheel is fixedly connected with an output shaft of the servo taking-up and paying-off motor, one end of each rope is fixed to the rope wheel, and the two ropes are the same in winding direction. The other ends of the ropes are fixedly connected with blade rotary shafts, one end or the middle of each blade is fixedly connected with the rotation center of the scissor fork type mechanism, the other ends of the blades are matched with the sliding rails, and the blades can move along the sliding rails but can not rotate around the rotary shafts of the blades. The wind turbine is installed by the adoption of a blade fixed pitch, and the radius of a wind wheel is controlled according to wind speeds, so that the pneumatic performance of the perpendicular shaft wind turbine is improved at different wind speeds. Meanwhile, the mechanics properties of the perpendicular shaft wind turbine are improved in a strong wind environment, even braking and shutdown stages can be avoided, and the working range of the wind turbine is greatly enlarged.