5,5-Thiobis-(2-(2-hydroxy -3,5 -di -tert -butylphenyl)-2H-benzotriazole)which have a benzotriazole and a disulfide bond was synthesized from 2-(2-hydroxy-3，5-di-tert-butyl)-5-chloroazimino-benzene and n-butyl mercaptan alkali metal salt，with 1-Methyl-2-pyrrolidinone in the absence of solvent .The structure was characterized by 1HNMR, FTIR, FABMS. The UV spectra were measured,the maximum UV absorption wavelength is 364nm, as compared with the ordinary commercial UV absorber wavelength is 353nm, and it has a very high molar absorptivity, up to 55000 L/(mol挠洀) in the maximum absorption wavelength, which is 2 times than the commercial UV absorber. It can protect plastics, coatings and person's skin from ultraviolet (320～400nm) damage. Has a wide application value.