Abstract: In order to prevent the increase of Cl^- concentration caused by seawater intrusion to affect the service life of underground water-sealing oil storage caverns, the evaluation and control methods of seawater intrusion are studied based on the construction of an underground oil storage cavern. The seepage field and solute transport characteristics of the underground storage cavern under the conditions without water curtain system, horizontal water curtain system, horizontal and vertical water curtain system are obtained by using the finite element numerical simulation method. The results show that the vertical water curtain system can enhance the convection of fresh water to flow to seawater around the cavern so as to prevent the seawater from invading the cavern. Only the horizontal water curtain system can not prevent the seawater intrusion, but the vertical water curtain system must be set up to completely restrain the seawater intrusion. On the premise of restraining seawater intrusion, the reservoir water level can meet the requirements of water sealing, but the inflow of water increases. The research results may provide a theoretical basis for the selection of prevention measures for preventing seawater intrusion by the water curtain system of underground water-sealing oil storage caverns in coastal areas.