Abstract: In multiphase pumps transporting gas-liquid two-phase flows, the high-speed rotation of the impeller induces complex deformations in bubble shapes within the flow domain, making the prediction of gas-liquid two-phase drag forces highly challenging in numerical simulations. To achieve precise prediction of the drag forces on irregular bubbles within multiphase pumps, this study modifies the existing bubble drag force model and applies the revised model to the prediction of gas-liquid two-phase flow within multiphase pumps. The research findings indicate that the modified drag force model significantly enhances the accuracy of predicting flow characteristics within the pump, particularly under high gas volume fraction conditions. The simulation results for gas phase distribution and vorticity exhibit strong agreement with experimental data. The modified drag model better captures the accumulation of the gas phase at the suction side of the impeller outlet. It also accurately predicts the vortex characteristics induced by bubble backflow from the trailing edges of the diffuser. Additionally, the adjustment of the drag coefficient enhances the model’s ability to represent local flow field characteristics, thereby optimizing the performance simulation methods of multiphase pumps. Compared to traditional drag force models, the modified model reduces prediction errors in head and efficiency by 36.4% and 27.5%, respectively. These results provide important theoretical foundations and model support for improving the accuracy of gas-liquid two-phase flow simulations and optimizing the design of multiphase pumps under high gas volume fraction conditions.