Abstract: The performance of multiphase pumps, the core equipment for marine oil and gas transportation, is critical, and the tip clearance is a key factor affecting their work performance. Currently, the effects of flow rate on the performance of multiphase pumps under different tip clearances remain unclear. Therefore, based on a self-developed single-stage helical axial multiphase pump model, the effects of different flow rate conditions under varying tip clearances on the internal flow field and energy characteristics of the pump were systematically investigated by combining numerical simulation and experimental validation. The results indicate that the tip clearance amplifies the disturbance of flow rate variation to the flow field; under the conditions of a large tip clearance and a large flow rate, intense relative velocity fluctuations are induced in the middle section of the impeller by the tip leakage vortex; under a small tip clearance, the energy is dominated by static pressure energy, and the work performance is stable and efficient; whereas a large tip clearance causes a negative static head at the front section of the impeller, and the dynamic head replaces the static head as the dominant factor within the impeller, which severely damages the pressure-boosting performance of the pump. Under different tip clearances, with the increase of flow rate, the total power and static power gradually increase, and the proportion of static power in each section exceeds 50%.