Abstract: The isolation,identification and antifungal activity of the active metabolite of the endophytic fungi Trichoderma harzianum from Llex cornuta Lindl.were studied.The fermentation liquor of the endophytic fungi was extracted by ethyl acetate and purified by silica gel and reversed phase chromatography(ODS).A trichothecene compound was obtained and its structure was identified as 4β-acetoxy-12,13-epoxy-9-trichothecene(trichodermin) by IR,MS and NMR.The compound was separated from the metabolite of Endophytic Fungi for the first time.The EC50 values of trichodermin inhibiting the mycelia growth of Alternatia solani and Rhizoctonia solani were 3.35 and 3.59 mg/L,respectively.In addition,protective effects and therapeutic effects of trichodermin at 100 mg/L against A.solani and R.solani were 97.8%,98.1% and 96.7%,97.3%,respectively.