Hydraulic jet pump is one of the mixing-reaction equipments using high-speed jet for work force to deliver energy and mass of fluid. Many factors affect the efficiency of this pump, and the mechanism is very complex. The present work aims to study the influence of different hydraulic structures on the efficiency. Based on computational fluid dynamics, two-dimensional oil flow in hydraulic jet pump with different structural parameters (area ratio, throat length and spray distance) was simulated. Calculation results show that: area ratio determines the suction capacity, throat length determines the mixing efficiency, and spray distance determines the outlet pressure. Since numerical simulation method can reduce experimental expenses and design cycle, our approach may provide some references for safe design and engineering practice of hydraulic jet pump.