In order to understand the processes of pollen germination and embryo development of jackfruit, fluorescence microscope technique, whole stain-clearing technique and paraffin sections were employed in this experiment. Results showed that, pollens germinated around 6 h after pollination; pollen tube entered into the style 12 h after pollination; pollen tube entered into the ovary 72 h after pollination. Endosperm began to divide before zygote at the 9th day after the flower had withered. Embryo finally matured through developments of globular embryo, heart- shaped embryo and cotyledon embryo, which was at 16th, 18th, 21th day after the flower had withered, respectively. Fertilized polar nucleus developed into cellular endosperm. Seed failure could result from embryo sac abortion, ovules abortion and unfertilized embryo sac.