The operating principle of the self-priming pump is that the pump is filled with water (or the water in the pump case itself) before the pump is started. Start after high-speed rotating impeller flow to the vortex in the impeller, shell, then the entry form the vacuum, the inlet non-return door open, within the air into the pump suction tube and the impeller, to arrive at the outer edge. Self-priming pump is a self-priming centrifugal pump, which has the advantages of compact structure, convenient operation, smooth operation, easy maintenance, high efficiency, long service life, and strong self-priming capability. The pipe does not need to install the bottom valve, only to ensure that the pump body has the quantitative primer before work. Different liquid can be used with different material self-priming pump.