The impeller is installed in the pump casing 2 and fastened on the pump shaft 3, which is driven directly by the motor. A liquid suction 4 is connected to the suction pipe 5 in the center of the pump casing. The liquid enters the pump through the bottom valve 6 and the suction pipe. The liquid discharge port 8 on the pump casing is connected to the discharge pipe 9. Before the centrifugal pump is started, the pump casing is filled with the liquid being transported; after starting, after the start, the impeller is driven by the shaft to rotate at high speed, and the liquid between the blades must also rotate. Under the effect of centrifugal force, the liquid is thrown from the center of the impeller to the outer edge and obtains energy, leaving the outer edge of the impeller at a high speed and entering the volute pump casing. In the volute, the liquid decelerates due to the gradual expansion of the flow channel, and then converts part of the kinetic energy into static pressure energy, and finally flows into the discharge pipe at a higher pressure and sends it to the required place. When the liquid flows from the center of the impeller to the outer edge, a certain vacuum is formed in the center of the impeller. Because the pressure above the liquid level of the storage tank is greater than the pressure at the inlet of the pump, the liquid is continuously pressed into the impeller. It can be seen that as long as the impeller continuously rotates, the liquid will be continuously sucked in and discharged.