The lifting hole is one of the important perforations of ship cabin and one of the main leakage sources.Therefore,it is necessary to carry out the research on the leakage rate prediction and control of bolt flange gasket sealing structure of lifting hole.The contact interface was considered as a complex microporous structure,based on the porous media seepage theory,the quantitative relationship between the contact interface microporous structure and its deformation and gas transport was defined,and the leakage rate mechanism model of contact seal was constructed.By combining the macroscopic mechanical analysis with the microscopic leakage mechanism analysis,this model is independent of the experimental regression coefficient,which has important guiding significance for the design of nonstandard flange sealing structure.Combined with the threedimensional finite element mechanical analysis,the model was applied to the prediction of the leakage rate of the boltflangeconnection structure of the lifting hole,and the influence of various factors was quantitatively analyzed,including bolt preload,flange width,gasket thickness,bolt number,bolt diameter,etc.The results show that the leakage rate under high media pressure can be reduced by increasing the preloading force,the thickness of gasket or the number of bolts,while changing the diameter of bolts has no effect on the leakage rate.Taking the minimum leakage rate as the index,the orthogonal test method was used to optimize the design of the lifting hole seal structure.It is found that the leakage rate under the optimal scheme is decreased by 37% compared with the maximum leakage rate.