Abstract: A large number of seals made of nitrile butadiene rubber (NBR) are used in power equipment to ensure the safe and stable operation of equipment. In a hot and humid environment, the performance of seals is easy to deteriorate due to aging, and shows different aging characteristics. In order to research the aging characteristics and mechanism of NBR, NBR samples were selected to carry out the comparison tests of wet heat aging and hot air aging. The weight, compressive permanent deformation and mechanical properties of the samples were measured during the aging process, and samples were analyzed by Fourier transform infrared spectroscopy (FTIR), thermal analyzer and scanning electron microscope (SEM). The results show that the mechanical properties of NBR are significantly reduced after wet heat aging and hot air aging, and the compression set of samples in the hot and humid environment is significantly higher. In hot air aging, chain breaking and crosslinking of NBR are very active and eventually reach equilibrium. Different from the hot air environment, the hot and humid environment is advantageous to the migration of additives such as antioxidant protection. In this process, NBR loses the protection of additives such as antioxidants, thus NBR is more easy to aging because of cross-linking and oxidation, and permanent deformation is more likely to occur when it is affected by external stresses.