In order to improve the performance and enhance the working capability of the impeller within a multiphase pump, the pressurization performance of a multiphase pump impeller was investigated under different flow rates and gas volume fractions with the standard k-ε turbulence model. It is shown that the position with a large pressure difference across blade pressure and suction sides is located in the first half portion of blade from the blade leading edge, especially the closer to the impeller rim the first half portion is, the stronger the pressurization performance is; in the second half portion of blade, the closer to the rim the portion is, the poorer the pressurization performance is. At different flow rates, from the impeller inlet to the outlet, as the flow rate increases, the pressure difference across blade pressure and suction sides decreases gradually. At different gas volume fractions, the higer the gas volume fraction, the greater the effect of gas fraction on the pressurization performance of the impeller; further, with gas volume fraction increasing, the pressure difference drops off faster. These results provide an important theoretical basis to further design for multiphase pump impellers.