The strains belong to Enterobacer spp. and Citrobacter spp. were tested to degrade gallic acid to product pyrogallol in the CDM medium thought the substrate induction test, and Enterobacer aerogenes was screened as the stable high-yielding strain of pyrogallol. Fermentation temperature、substrate concentration、initial pH of fermentation medium and such influence factors which could effect the yield of pyrogallol were explored, then designed 3 factors 3 levels of response surface in the Box-Behnken experimental analysis and model modification, in order to determine optimum fermentation conditions of Enterobacter aerogenes. The verified experiment results showed that the yield of pyrogallol could reach to 77.86% when the fermentation temperature was 32℃, substrate concentration was 0.32%, and pH of the initial fermentation medium was 6.0, and the yield was better than the chemical method or other biological method in the similar condition, so the study could direct the industries to prepare the pyrogallol from gallic acid thought the biological processes.