Abstract: In order to explore the physiological and biochemical changes in the germination process of peony seeds, the dry and fresh weight, water content, seed vigor, anatomical structure, soluble sugar content and endogenous hormone content of peony seeds at different development stages after full-bloom stage were observed and measured. The results showed that the seed coat became thinner, starch degraded, and the endosperm enriched and accumulated starch during seed development, and the dry and fresh weight of seeds reached the highest at 100 d after flowering, while the water content reached the lowest at this time. The activity of endosperm cells was the highest at 50 d after flowering while the soluble sugar content reached the highest level at this time. Also, the content of endogenous hormones changed significantly and fluctuated greatly. In summary, studies had shown that the development of peony seeds was accompanied by the rise and fall of endogenous hormones content, significant physiological and biochemical changes, large accumulation of starch and soluble sugar, and the physiological process was more complex.