To meet energy-saving and environment-protective purpose, a series of plastic pumps are developed by composite molding. There are four key techniques involved, firstly, plastic hydraulic components with light-weight; secondly, steel barrel as a pump casing and a connection component as well; thirdly, floating impeller strategy where impeller is drifting freely along shaft; and lastly, a self balancing impeller technique which can totally keep axial force balancing. The manufacturing process is energy-saving, and the components can be recycled, which have great potentials for conservation of environment.