Abstract: Underground water-sealed oil storage is usually built in integral crystalline rock masses. Based on the theory of water sealing, oil is stored in underground cavern. In the surrounding rock, typical fluid-solid coupling characteristics exist in the process of construction and running. Based on flow-solid coupling theory of fractured rock mass, COMSOL Multiphysics software is used to simulate the fluid-structure interaction of surrounding rock under different working conditions. Research results show the follows. Without setting water curtains the underground water level at top of the cavern decreases obviously and forms the funnel, which could lead the spill of oil and gas. After the water curtains are set, the fall trend of water level is effectively controlled and the sealing of cavern is ensured. With setting water curtains, obvious stress concentration appears in straight wall, vault and the corner points of floor. But the plastic zone still does not appear in surrounding rock. The maximum displacement of cavern does not exceed 1mm. Besides, the stability of surrounding rock is good. The results can serve as references to the design and construction of underground engineering.