Large size of Y-seal using in the pressing line was taken as a research object. Based on Ansys finite element software of probability design system (PDS) module, with the main size of sealing components, gas pressure and friction coefficient as random input variables and the maximum contact pressure and the maximum shear stress as response value, the probability distribution of response value was calculated. The reliability and sensitivity of the sealing components were calculated through the interference model of stress intensity. The reliability of the seal ring was verified, and the main parameters that are quite sensitive to reliability were determined. The analysis results of sensitivity show that the maximum contact pressure is obviously influenced by the seal lip opening width,seal lip length and the friction coefficient. The impact of seal lip length on the maximum shear stress is very obvious, therefore, particular attention should be paid to control of these parameters during designing and manufacturing.