An important organic intermediate 2-bromophenol can be prepared by the tert butyl transfer reaction of toluene with 2-bromo-4-tert-butyl phenol. The effect of catalyst and the reaction condition on the tert butyl transfer reaction of 2-bromo-4-tert-butyl phenol were investigated. The results show that aluminum tri-chloride and its complex salt with tertiary amine and hydrogen chloride are active in the reaction. The analysis of 27Al NMR shows that the real catalytic species may be chloroaluminate, which formed by the reaction of aluminum trichloride with hydrogen chloride from the hydrolysis of aluminum trichloride. Further, the hydrogen chloride and hydrogen bromide are proved to be the aluminum trichloride activator, and the dosage of aluminum trichloride can be reduced. The optimized process condition is as followed : 4-tert butyl phenol reacted with bromine at 0℃in dichloromethane selectively forming 2-bromo-4-tert butyl phenol, then,2-bromophenol can be prepared through “one pot reaction” by adding aluminum tri-chloride and toluene in molar percentage of 30 and 600 at 30℃. The conversion and selectivity of 2-bromo-4-tert butyl phenol are of 96.5% and 99.6%, respectively.