Impeller，radial guide-vane and volute of a two-stage self-priming centrifugal pump were designed with velocity modulus method．
The two-stage self -priming centrifugal pump was made and the hydraulic characteristic experiment and self -priming experiment were measured．The results show that efficiency of the pump reaches 60．58% at the design flow rate． The range of high efficiency area is broad．
Efficiency of the pump is always above 58% from flow rate of 52 to 85 m3 /h． In addition，the self-priming time of the pump is 154 s when the self-suction height is 4 m