Abstract:The embryogeny from zygote to seed embryo and the seedling development from seed to seedling of Hydrilla verticillata were studied in this paper. They were discovered that the 1-2 celled suspensor, the developed shoot end and undifferentiated root end of embryo, the root end differentiated after seed germinating, the root collar and hypocotylar hair arised from the top of the meristematic zone of the primary root in seedling of Hydrilla verticiliata are same as Alisma orientale, and these characters were discussed finally.