The ultrastructure of spermatozoon in Glaucomya chinensis was observed with transmission electron microscopy.The mature sperm is typical primitive type,including the head,middle piece and tail.The head consists of acrosome and nucleus,and the acrosome takes the shape of inverted"V".The elongated cylindrical nucleus has a posterior nuclear pocket but has no front nuclear pocket.Four large mitochondria and two centrioles make up the middle piece.The flagellum is slender and shows the typical"9 + 2 " microtubular structure.This article also discusses the morphological differences of sperm structure among lamellibranches species.