Abstract: Studies on water quality of Haihe River Basin show that pentachlorophenol（PCP）has become the major organic pollutant. As a result，to control the pollution of PCP has become vital for the pollution control in Haihe River Basin. The influence factors of photocatalytic degradation of PCP were studied and analyzed. First，photocatalysis assisted by three oxidants（O2，H2O2，K2S2O8） was investigated in terms of techbnology，environmental impact and economy，and it showed that O2 was the optimal choice. The reaction conditions of photocatalysis，including pH of solution，circulation flow rate，light intensity，dosage of catalyst，were investigated with the orthogonal method. The result showed that circulation flow rate was the least significant factor for the reaction，and the degradation rate of photocatalytic reaction increased with the pH of solution and light intensity，and there was a peak of dosage of catalyst.