Abstract: In this study, the ultrastructure of seed coat and endosperm ingredients of Cercis chinensis seed was systematically investigated by using scanning electron microscope(SEM)and transmission electron microscope(TEM)during the process of maturity. SEM images showed that during the early stage of maturity some pores appeared at the surface of seed coat, and then disappeared with the subsequent development of seeds. At a later stage, waxy of seed coat appeared and became thicker as the seed matures, and micropyle and hilar groove cracked gradually. By the longitudinal section of seed coat, we found that the palisade layer near hilum formed earlier than the middle part of seed coat and the palisade cells in this area was monolayer. One hundred and five days after blossoming, a water entry from the hilum extending along the seed coat could be observed. A reticular tracheidal bar from hilar groove to the opposite end was found in the water entry pathway while 135 days after blossoming. After seed maturation, from the exterior to the interior, the seed coat of C. chinensis consisted of three layers: the waxy cuticle, the palisade layer and the parenchymatous layer. The cuticle was composed of wax and the other covering. The palisade layer consisted of a monolayer macrosclereids with thick walls elongated longitudinally. The macrosclereids were tightly arranged. The waxy cuticle and the palisade layer may be the main barrier controlling the entrance of water through seed coat. By the TEM, we found that at the early seed-filling stage, the endosperm cells were characterized by a large central vacuole with a small quantity of lipid droplets and density electron substances. As the maturity of seed, mitochondria, endoplasmic reticulum and Golgi apparatus formed and then degraded gradually. Meanwhile, the quantity of lipid droplets and density electron substances were increased continuously. It indicated that with the development and maturity of seed,the storage macromolecules accumulated and the metabolism decreased continuously, after which the seed turned to dormancy.