As one of the key parameters of seed quality, seed longevity is directly related to seed germination, the growth and development of young seedlings, and finally the crop yield. Seed longevity is a complex biological process which regulated by numerous exogenous and endogenous factors, such as structure, nutrient composition and related key genes. Investigating the changes of physiological and biochemical indices, biological function of the related genes during seed storage process to reduce the energy consumption of seed, is great significant to further extend the longevity of seed. In this review paper, we summarized the physiological and molecular mechanisms, related key genes which have dominant roles on the changing of seed longevity. Furthermore, the regulation mechanisms of various external indices on seed longevity are discussed. Finally, we discussed probable research directions in the future.