In this paper, the effects of operating parameters such as UV light wavelength, initial pH, reaction temperature and hydrogen peroxide concentration on decolorization of metal complex dyes (Neutral Bordeaux GRL, Neutral Pink BL and Neutral Blue BNL) by UV/H2O2 process were studied in detail. The results showed that the decolorization rate constants were obviously enhanced with the increase of UV intensity. In UV (254nm)/H2O2 system, 94.4% decolorization of Neutral Bordeaux GRL, 99.2% decolorization of Neutral Pink BL and 65.4% decolorization of Neutral Blue BNL were achieved after 60 min reaction. The results also indicated that both suitable amount of H2O2 and initial pH were needed for effective decolorization of different metal complex dyes. The reaction activation energy of Neutral Bordeaux GRL, Neutral Pink BL and Neutral Blue BNL were 3.43, 14.4 and 23.39 KJ mol-1, respectively.