3-D simulation was performed for the gas-liquid two-phase turbulent flow in self-priming pump by using Fluent software with Mixture model, SIMPLEC algorithm and Realizable turbulence model. The gas-liquid two-phase flow in self-priming pump was investigated in the pressure in the pump, the velocity in the pump, the distribution of gas and liquid phase in the pump. To some extent, the results reveal the self-suction process of the two-phase flow in self-priming pump, and provide references for self-priming pump design.