Abstract: Confocal laser scanning microscopy is a powerful tool in studying the structure of tissues and cells because of the function of scanning like "CT scanning. In this study the tool is used to study systematically on the double fertilization, embryogenesis and endosperm development in autotetraploid rice, Guangluai No.4-4x and L202-4x. The characteristics of development of embryo sacs were described at different time after fertilization. Double fertilization, embryogenesis and endosperm development in autotetraploid rice were the same as those in diploid rice. Some abnormalities, including non-embryo, embryo sac without endosperm, embryonic diapauses，embryonic degradation etc. were found in autotetraploid rice. Abnormal difference in fertilization and embryo development was found between the two autotetraploid rice. The abnormalities maybe causes the seed setting drop in autotetraploid rice.