Vertical axis wind turbine and blade thereof

The invention discloses a vertical axis wind turbine and a blade thereof, the blade is a blade with a wing-shaped cross section, the blade is divided into a first main body and a second main body between the front edge and the tail edge of the blade, and the first main body and the second main body can move relatively along the height direction of the blade; the cross section is perpendicular to the height direction. The blade is divided into the first main body and the second main body, the first main body and the second main body can move relatively in the height direction of the blade of the airfoil, and when the rotating speed of the blade is too high, the aerodynamic shape of the section of the blade can be changed through the relative movement of the first main body and the second main body; large flow separation occurs at the tail part of the first main body and the front end of the second main body, the section lift force is greatly reduced, and the section resistance is greatly increased, so that the