Defoamer capable of improving transmission stability of impeller

The utility model provides a defoamer capable of improving the transmission stability of an impeller. The defoamer comprises a motor, a middle sleeve, a main shaft, the impeller, a fixed seat, a mechanical seal and a rotating piece, the output end of the motor is in transmission connection with the main shaft, the middle sleeve is fixed on the side wall of the motor, the other end of the middle sleeve is fixedly provided with the fixed seat, and the main shaft penetrates through the middle sleeve and the fixed seat and then is connected with the impeller; the mechanical seal is arranged on the circumferential surface of the main shaft and connected with the bottom of the middle sleeve, so that the middle sleeve is sealed; the rotating piece is rotationally connected to the circumferential face of the main shaft and connected with the inner wall of the fixing base so as to be matched with the mechanical seal to provide two supporting points for the main shaft. The main shaft is provided with two supporting poi