Attempts were made to develope the method of biological control by application of hyperparasitism on plant disease. The hyperparasitic fungi used in this work was Trichoderma sp. which was isolated from the ginseng growing soil, and the host fungi were Fusarium oxysporum Schlecht and Glomerella cingulata(St) Spau. et Schr. The hyperparasitic fungi identified as Trichoderma viride. It was observed that the hyperparasitic fungi either contact and penetrate into the hyphae of the host or inhibit the growth of host finally destroy of the host cells.