Seeds are important reproductive organs of seed plants. In natural ecosystems, seed germination indicates that the plants have started a new life cycle, and the high quality germination of crop seeds determines its yield. However, seed germination is a complex and delicate process, with seeds undergoing drastic changes at the molecular and physiological levels within a short period. This process is susceptible to the combined effects of various internal and external environmental factors. This review introduces the research progress of the regulation mechanism of seed germination, with a particular focus on environmental factors, including water, temperature, light, and small molecule substances, influence seed germination. It is expected that varieties with good germination rate can be customized in the face of complex agricultural production environment.