The characteristics of embryonic development and glochidia structure were observed in Lamprotula leai by means of light microscopy.The results showed that the isolecithal fertilized eggs developed synchronizedly in the inner and outer gill of the female.The embryonic development of L.leai could be divided into 6 stages:oosperm,cleavage,blastocyst,gastrulae,glochidia in membrane and glochidia.The cleavage was holoblastic and spiral.The unfertilized egg degenerated in the gill.There were relations between different stages of the embryonic development and the colours of the embryo and the inner and outer gill of the mother.All embryos would expel from the gill when the environment of mussel had changed.The data on embryonic development character could be used for guiding artifical breeding of L.leai.