Abstract: The gas-liquid two-phase flow of water ring vacuum pump is very complex,and it is difficult to accurately describe the flow law by using the relevant fluid mechanical theory analysis,which increases the difficulty of the design and development of new products of water ring vacuum pump to a certain extent. In this paper,a threedimensional transient computational fluid dynamics(CFD)model of 2 BEA-703 water ring vacuum pump is established. Firstly,through numerical simulation,the phase distribution,pressure distribution and streamline distribution of fixed section in impeller and pump cavity are analyzed,and then the influence of different speeds on the internal flow field of water ring vacuum pump is analyzed. According to the analysis of the simulation results,the gasliquid interface in the pump is accurately captured,and the flow law of gas-liquid two-phase flow is revealed. The research results are used in the aided design and manufacture of the new water ring vacuum pump to ensure the realization of the design index of the product.