The invention relates to a wind sail-opened vertical short axis large-scale wind turbine generator, which belongs to the technical field of green energy. The invention aims at solving the technical problems of too large start wind speed (a fan is in a stopped state at most of the time), expensiveness and running noise of a machine and the like of the existing horizontal axis blade wind turbine. The technical proposal adopts a principle that wind sails capture wind energy to solve the above problems. The wind sail-opened vertical short axis large-scale wind turbine generator comprises a tower frame, a rotating tower (a vertical short axis), multiple layers of cross wind sails that can be opened and closed, wind sail beams and the like. The multiple layers of the wind sails on the rotating tower are opened sequentially automatically at a windward side and are closed sequentially at an upwind side, thus enabling the rotating tower to rotate continuously and stably, kinetic energy is transmitted to a variable speed constant frequency generator through a gear and a chain, and the generated electrical energy is merged into a power grid; and the wind sails consist of weather resistant medium-alkali glass fiber clothes and thin-wall light steel frames, the multiple layers of the opened wind sails have a large area, are in the shape of a concave semi-cylinder, and can be opened in light wind, the noise is low when the machine runs, and the manufacturing cost is greatly reduced.