Abstract: The shaped storage tank has more advantages than the traditional long-column and spherical storage tank in improving the utilization efficiency of structural space and bearing load. Holding fuel without leakage is the most basic requirement of the power system for the storage tank. In view of the problem that the strength and stiffness design of composite storage tank are the main design, and the sealing anti-leakage design is not considered enough, this paper takes a special type of composite storage tank as the research object to carry out anti-leakage design and analysis. Firstly, the reliability of the sealing coating is verified by identifying the leaky parts, designing typical components and performing pressure test, combined with non-destructive testing and fracture micro-structure analysis. Based on the test results, the simulation analysis of typical component charging test was further carried out, and the allowable opening displacement of HM-111 sealing coating was preliminarily deter-mined by considering the influence of size effect on sealing performance. Finally, the structure design of the composite special-shaped tank is carried out. Considering the rigidity and strength, the allowable opening dis-placement of the sealing coating is introduced. By comparing with the experimental results of the pressure test of the tank, the opening displacement as the failure determination of the sealing coating can meet the requirements of the anti-leakage design of the tank.