A cooling system and method for a wind power generator and a wind power generator set. The cooling system for a wind power generator includes air extraction pipelines and air discharge devices. The air extraction pipelines are located inside a generator case. A pipeline inlet in communication with a generator, a first pipeline outlet in communication with the outside of the generator case, and a second pipeline outlet in communication with the inside of the generator case are arranged on the air extraction pipelines, and the first and second pipeline outlets are provided with air doors.