Abstract: To reveal the gas distribution in the multiphase pump impeller passage, based on the standard k-ε turbulence, the air and pure water were used as two-phase media, and the Fluent software was employed to simulate the two-phase flow state under the inlet gas volume fraction of 30%, and the gas distribution characteristics under different blade spans were analyzed. Results show that the gas volume fraction near the hub of first stage impeller pressure side is the largest. However, the gas volume fraction on the second and last stage impeller pressure side is almost the same. From the impeller inlet to outlet at 0.5 span in difference compression stage, the gas volume fraction on the first stage impeller suction side is larger than that of the second and last stage impeller. The difference of the gas volume fraction on the pressure side from the hub to the shroud between the first stage impeller and second or last stage impeller is gradually decreased. However, the suction side is gradually increased. The results provide a reference for improving the efficiency and stability of a multiphase pump.