To investigate the effect of surface morphology of metal gaskets on leakage rate,the local scanning of Cu,Al and 316L metal gaskets with different surface roughness was carried out by 3D morphometer,and the real microscopic contact model of flange gaskets was constructed.The statics and computational fluid dynamics analysis was carried out to investigate the influence of surface roughness and contact pressure on the leakage rate under different medium pressure by setting different boundary conditions in the fluid domain.The simulation results show that the metal gaskets of three materials exhibit a trend of greater surface roughness leading to greater leakage rate.Among them,the leakage rate of Al gasket is the most sensitive to surface roughness,while the leakage rate of 316L gasket is the least affected by surface roughness.When the surface roughness is constant,the greater the applied contact pressure,the lower the leakage rate.However,when the contact pressure reaches a certain value,the effect of increasing the contact pressure on reducing the leakage rate will become smaller and smaller.