Abstract: The structure and the working theory of a new type of double-stage pump combined with diffuser and volute are introduced, which runs more steadily at high speed. With this structure, the kinetic energy of the flow out of the tunnel of impellers is translated to pressure energy, the velocity circulation is eliminated, and the radial force is reduced. In the pump inlet, the vortex-diminished was inset. It can resolve the problem of capitation at high speed, support the bear of the pump, and improve the hydraulic performance of the pump. The design method of the pump was discussed, the test results of performance were given, and the advantages of the pump were summarized. The test data show that the design is successful with 8% higher efficiency than the design requirements, and the value of the pump cavitations is 0.7　m lower than that of the national standard. Moreover, the total weight of the newly-designed pump was reduced by 30%.