Abstract: In order to investigate the effect of impeller blades number on the external characteristics, working and hydraulic performance in a multiphase pump, based on the Eulerian heterogeneous flow model, CFX software was used to carry out numerical calculation of multiphase pump with different number of impeller blades under diverse flow conditions and the inlet gas void fraction was 10%. The present study shows that the impeller blades have a petite effect on the decrease trend of head and efficiency when the flow rate is below 90 m³/h. When the flow rate increases gradually, four impeller blades lead to an increase in the descending gradient of head and efficiency, the external characteristics, static pressure distribution on the blade surface, load distribution and hydraulic characteristics of the multi-phase pump were better when the impeller blades is 3 than 4. The results of the study can provide reference for the selection of the impeller blades of multiphase pump.