In order to research the sealing characteristics of the hatch door of a near space manned capsule,a finite element simulation of the compression behavior for P-ring of the hatch door was implemented.The variation of primary or subsidiary seal face width and contact stress with the compression distance of hatch door and different seal clearance was analyzed,and the recommended values of compression distance of hatch door and different seal clearance were given.Based on ROTH leakage model,the total leakage model was deducted,and the steadystate leakage was calculated and verified based on the leakage test.The calculation result of the total leakage rate calculated has good agreement with test result,and the validity of leakage rate model is verified