Abstract: The photocatalytic oxidation of phenanthrene in TiO₂ powder suspensions by some factors has been studied in the flask illuminated with a 15 W UV lamp.These factors are Al³⁺,Fe³⁺,H2O₂ ，pH,initial concentration,dosage of TiO₂ and loading silver.The results show that Al3+,Fe3+,H2O2 and loading silver can accelerate the degradation of phenanthrene.With the increase of TiO₂ ,the degradation rate increases,but it can prevent phenanthrene from degrading at a high dosage.In the acid condition,phenanthrene is easily degraded.There is negative first order reaction kinetic relationship between initial concentration and reaction rate.