Abstract: 【OBJECTIVE】 In allusion to the quality of hybrid rice kernel, we would like to study the relation of the chalkiness formation and the development of endosperm structure and starch granule of hybrid rice parents, so as to be convenient for the clarification of high chalkiness of hybrid rice. 【METHOD】 The chalkiness characters were investigated as GB/T17891-1999. The endosperm structure and starch granules were observed with scanning electron microscope (SEM). 【RESULTS】 The results showed that the remarkable difference of chalkiness characters between maintainers and restorers of hybrid rice was grains with chalkiness (PGWC) and degree of endosperm chalkiness (DEC), while square of chalky endosperm (SCE) had no distinctive difference between maintainers and restorers. Chalkiness of maintainer was easily produced in the middle and abdomen of kernel, while that of restorer was only produced in the middle. The distribution uniformity of starch granule in the kernel transect correlated with chalkiness. The starch granule was more uniform, the chalkiness in kernel was much less. But the cuboid cells in endosperm were not the key parameter affecting chalkiness formation. Almost all of the maintainers and restorers could develop the starch granule in kernel backside all right and badness in middle kernel. The main difference of starch granule between maintainers and restorers was in abdomen of kernel, where starch granule developed well in restorers but badly in maintainers. 【CONCLUSION】 The chalkiness positions are different between maintainers and restorers of hybrid rice parents. It has an important relation with the starch distribution in endosperm. The heteroplasia of starch granules in center and abdomen of endosperm easily leads to come into being chalkiness. The development of starch granules is closely relevant to the transport way of filling materials.