Submersible pump is one type of water treatment equipment with wide range of usage. Compared with normal water pumps, the submersible pump works under the water, but normal water pumps works on the ground. Before starting the submersible pump, the suction pipe and pump insides must be filled with liquids fully. After starting the submersible pump, the impellers revolve with high speed, and the liquids inside the pump revolve together with vanes. Under the action of centrifugal force, the liquids fly away from the impellers and eject outsides. The speed of the liquids ejected slows down in the pump casing diffusion chamber, at the same time the pressure of the liquids ejected increases, lastly the liquids discharge from the submersible pump discharge pipe. In the center of vanes, because the liquids are thrown towards around, there is one vacuum low pressure zone. The liquids in the pond or well are sucked into the submersible pump through the suction pipe under the action of atmosphere on the level of the pool or well. In this way, the liquids are sucked into the submersible pumps continuously and discharged from the pump discharge pipe continuously.