Abstract: The Rhizoctonia solani metabolites in potato was investigated. Firstly,the culture filtrates of Rhizoctonia solani were extracted with different organic solvent and the biological activities of each fraction were examined.Then,the toxic components were purified with method of thin layer chromatography( TLC) and silica gel column chromatography.Finally,Rhizoctonia solani toxin was analyzed and identified by UV absorption spectrum,FT- IR spectra and gas chromatography- mass spectrometry( GC- MS).The results showed that the component extracted by ethyl acetate showed higher toxicity than that extracted by chloroform.Five Rhizoctonia solani isolates( I_1,I_2,I_3,I_4,I_5) were isolated by silica gel column chromatography.The absorption bands of the UV spectrum suggested that I_1 had a higher absorption at 198.5 nm. The IR spectrum showed bands characteristic of- CH_2( 2927.41,2856.06 cm~(-1)),C = O( 1735.62 cm~(-1)),C = C( 1635.34 cm~(-1)),-CH_3( 1417.42 cm~(-1)) and-C-O( 1263.1,1128.2 cm~(-1))groups in I_1.GC- MS analysis showed that I_1 mainly contains several substances of tributyl phosphate,diisobutyl phthalate,dibutyl phthalate and( methoxymethyl) triphenylphosphonium chloride.