Abstract: The oogenesis of Lygodium japonicum（Thunb.）Sw.was studied by histochemical method in thisstudy.The results of PAS reaction showed that the extracellular viscous substances of neck canal and ventralcanal cells were polysaccharides;there were plastids and rich starch granules in cell of archegonium in the earlystage of oogenesis,with the development of archegonium,the number and volume of starch granules in the eggand neck canal and ventral canal cells gradually decreased,and finally degenerated and disappeared.Theresults of Sudan black B reaction showed that the extracellular viscous substances of neck canal and ventralcanal cells of L.japonicum also contain lipids,but there was no obvious lipids production in egg cells.Comprehensive studies showed that there was no accumulation of carbohydrates or lipids in the plasmamembrane of egg cells.From the perspective of histochemistry,this study confirmed the particularity of L.japonicum,it had the characteristics of both primitive ferns and evolutionary ferns.