Abstract: The ultrasturcture of the spermatozoon of Hyla chinensis was studied in this paper and its significance on the phylogenesis was roughly inquired.The spermatozoon consisted of a head and a tail.In the head there was a stick-like nucleus with highly condensed chromatin in it.A coneshaped acrosome lied anterior to the nucleus.There was a subacrosomal cone and some small vesicles within the subacrosomal space.The tail of the spermatozoon was thin and long.It consisted of an axoneme,a dense fiber and mitochondria,but without an undulating membrane.Based on the fine structure of the spermatozoa of Bufonidae,Hylidae and Ranidae which had been studied so far,it was suggested that during the evolution of anuran amphibian the structure of the sperm tended to simplify.The complexity of the sperm structure of Hylidae was situated between Bufonidae and Ranidae,but was more similar to that of Bufonidae.Within Hylidae,the structure of the spermatozoon of Hyla chinensis was simpler than that of other species which had been studied in Hylidae.It was suggested that the reduction of the undulating membrane and the reduction (or the fusion) of the accessory fibers in the spermatozoon tail could be considered as advanced features of Hyla chinensis.