To explore the influencing factors of vivipary occurrence of Brassica napus L., yellow seed varieties‘410’ ‘456’‘552’ and black seed variety‘492’were used to study vivipary occurring stage, the effects of environment on vivipary and the relationship between the vivipary and the morphological and related physiological indexes of seed, by means of flowering stage marking, periodic sampling, morphological and physiological analysis. The results showed that the vivipary of four varieties occured mainly in embryo enrichment stage(27-36 d after flowering), and the initial vivipary percentage was 2.44%-3.90%, and the earlier vivipary occurred, the higher vivipary rate obtained. The thousand grain weight of seeds was significantly or significantly positively correlated with the vivipary percentage(r=0.84-0.97), and the moisture content was significantly negatively correlated with the vivipary percentage(r=–0.93- –0.98). External environment with high temperature and high humidity, the thin seed coat and relatively high lipase activity, soluble sugar content and respiratory intensity under enrichment stage of seed embryo were favorable for occurrence of seed vivipary. While there was no significant correlation between the electrical conductivity of seeds, total sugar content and the vivipary percentage.