Abstract: The thiobacillus ferrooxidans(T.f)s growth characteristics and mutagenic mechanism under the action of the ultraviolet radiation was studied. T.f was irradiated for 300s by ultraviolet lamp with 20W. The redox potential and pH in etching liquid were measured every 15s. The pH history and redox history were given, respectively. The optimal values of the redox potential and pH were 303mV and 1.98 respectively when T.f was irradiated for 240s. The mutagenized and strengthened T.f possesses of the better etching ability. It also has higher bacterial concentration and stronger oxidation active. The mini-gear structure is more distinct by using mutagenized T.f etching.