Abstract: For the newly developed distributed salient pole condenser, the rotor thermal duty greatly exceeds design experience. If the traditional cooling method is still using, the temperature rise will far exceed the limit of insulating materials and can not meet the technical requirements. In this paper, the technical solution of internal air-cooling of the motor rotor is proposed. Through the research of 3D flow-thermal field coupled simulation and full-current rotor temperature rise test, the major technical risks are eliminated and the key technical guarantee is provided for product development.