This paper presents a groundwater seepage model around the underground water sealed oil-storage cavern. According to hydrogeologic conditions and the structure of underground petroleum storage caverns and artificial water curtain systems, 3D numerical seepage simulation models are created respectively to simulate the groundwater flow nearby the caverns in three conditions： without water curtain system, with horizontal water curtain system, and with horizontal and vertical water curtain systems. In these three conditions, the extensions of the groundwater level contour are predicted and the variations of the groundwater level above the cavers are compared using the models. By the analysis of the comparison results, it shows that the extending range and rates of the groundwater level contour of the model with horizontal and vertical water curtain systems are less than other two kinds of conditions. So the artificial water curtain system plays an important role to assure the efficiency of the project and the safety of oil storage and also protect the groundwater environment.