Abstract: Observations were made to study the antifungal activities of Lampteromyces japonicus to pathogenic fungi such species as Botrytis cinerea,Fusarium moniliforme,Fusarium oxysporum,Rhizoctonia solani,Trichoderma viride,Phytophthora sp., Phytophthora nicotianae and Pyricularia oryzae for the first time.The results showed that L.Japonicus was all highly antagonistic to Botrytis cinerea,Fusarium oxysporum,Trichoderma viride,Phytophthora sp., Phytophthora nicotianae and Pyricularia oryzae.The antagonistic action to Botrytis cinerea,Fusarium oxysporum,Trichoderma viride and Phytophthora nicotianae was featured by their encircling of mycelia cake and culture filtrates of L.Japonicus,respectively.There was an inhibitory strip between the mycelias of L.Japonicus and Pyricularia oryzae .The antagonistic action of L.Japonicus was featured by its encircling hyphae of Phytophthora sp.and intruded into it.In addition,the hyphae of Phytophthra sp.were broken, and their cytoplasm became thinner and eventually dissolved.