Photocatalytic degradation of trichloroethylene(TCE) over $TiO_2$ was studied using the samples obtained by calcining $TiO_2$ at various temperatures. It was found that the reaction efficiency is mainly governed not by the variation of surface area but by the anatase/rutile ratio of $TiO_2$. As the acceptor of photogenerated electrons, $Cu^{+2}$ and $Fe^{+3}$ were introduced to $TiO_2$ by wetness impregnation. The reactivity was markedly enhanced by the loading of metal ions. At higher metal ion loading, however, the reactivity decreased with increasing metal ions loading, possibly due to the masking of surface active sites, such as hydroxyl group, by the metal ions. It was observed that the enhancement of reactivity by $Cu^{+2}$ is larger than that observed by $Fe^{+3}$. The enhanced reactivity of copper-loaded sample was attributed to the higher reducibility of copper.