The FZ self-priming pump has the self-priming function, which can pump the liquid below the installation position of the pump, and the performance is stable and the operation is simple, direct boot can, self-priming height can be determined according to the medium density in 2 to 4 meters, is the best choice to replace the bulky body of the underwater pump. The pump has the advantages of corrosion resistance, wear resistance, high temperature resistance, non-aging, high mechanical strength, smooth operation, advanced and reasonable structure, strict and reliable sealing performance, easy disassembly and maintenance, long service life. The FZ self-priming pump has a wide range of uses, such as pumping corrosive fluids from underground tanks to the target site, pumping acids and bases from acid-base tanks with no outlet at the bottom to the target site, or for circulation between multiple acid tanks, or used for unloading acid and so on.