Abstract: The Eulerian-Eulerian two-phase flow model used in the simulation of the the gas-liquid two-phase flow pump cannot consider the air bubbles diameter changing. There is a certain gap between the simulation result and the test when the gas content is relatively high. The MUSIG model,which is a new type of expansion model based on original Eulerian-Eulerian model, can calculate more accurately. Comparison with the experimental data shows that when the gas content is about 5%,the hydraulic characteristic curve calculated by the MUSIG model has a slight deviation from the experimental results,but the overall trend is in good agreement. Based on the original model,the flow characteristics inside the pump for different IGVF（ inlet gas volume fraction） show that the increase of the inlet gas content will cause entire flow instability and streamline turbulence; the gas phase will gradually accumulate in the middle of the should and the flow channel; the pressure of the impeller drops.These phenomena will gradually intensify with the IGVF increasing,and head and efficiency will decrease obviously.When the gas content is less than 3%,the internal flow is relatively stable; when the inlet gas content is 5%,the performance will suddenly drop,and the gas accumulation occurs in flow channel.