Abstract: Catechin was extracted and isolated from Tuo tea using S-extractor with trichloromethane as extractant at temperature of 95 ℃. The filtrate was concentrated by circum-evaporator, and caffeine in the filtrate was removed with methenyl chloride (V (methenyl chloride) : V (concentrated solution) = 3 : 1) as extractant. Then, the water phase was extrated further by adding ethyl acetate (V(ethyl acetate) : V(water) = 3 : 1) to get catechin extract. The column chromatography separation was performed with ethyl acetate (V(ethyl acetate):V(ethyle ether) = 4 : 1) as eluent and silica gel G as absorbent. The infrared spectrum of the potential structure of the extract of the Catechin was obtained by fourier transform/infrared spectrometry (FT/IR) with liquid film method, and many functional groups can be assigned by their characteristic vibration frequency. The mass spectrum was obtained by gas chromatography-mass spectrometry (GC/MS) and Catechin was identified by proposal fragmentation patterns of fragment ions m/z 152, m/z 139,m/z 124, m/z 123 and prominent ions. The study can help to offer the scientific basis for developing and utilizing Catechin.