Abstract: The seed is produced after double fertilization as a reproductive organ of higher plants. The size and quality of the seed serve as two main components that influence crop yield. In flowering plants, the seed comprises three major anatomical components, the embryo, the endosperm and the seed coat. Seed size is coordinately determined by the growth of the embryo, endosperm and maternal tissue. Exploring relevant factors that control seed development is crucial for improving crop yield. Recently, some mutants with seed developmental defects and QTL functions have been dissected by genetic and molecular biology methods. Related genes were found to regulate the development of embryo, endosperm and integument thus determining seed final size and yield. Most of these work were carried out in Arabidopsis and rice. Some reported work showed these genes function by integrating to the hormone metabolism or signaling pathway indicating plant hormone play key role during seed development, but the underlying molecular mechanism and gene regulatory network is still unknown. This article mainly focuses on the model plants of rice and Arabidopsis, reviewing recent progress in hormone-dependent regulation of seed development.