Vulcanization has an important influence on the performance of rubber seals. Modeling is an effective means of determining the optimal vulcanization process parameters. In the present study, the tribological and mechanical properties of ethylene-propylene-diene monomer (EPDM) samples with various degrees of vulcanization were analyzed, and a mathematical relationship between the degree of vulcanization and the properties was established. On the basis of the transient thermo-chemical coupling model of the vulcanization process, a finite element model was developed to solve the problems associated with the process parameters and product properties of rubber seals. The model can be used to evaluate the variation in sealing capacity and service life of seals produced under various vulcanization conditions to determine the optimal vulcanization parameters.