In order to treat the dyeing wastewater, the $UV/TiO_2/H_2O_2$ system was investigated, and proper pretreatment methods were examined to reduce the load on the system considering economical and technical efficiency. The results of this study were as follows: 1. $UV/TiO_2/H_2O_2$ system with pretreatment process was adopted, the result of Chemical coagulation and pH control units was $pH{;}11{;}{ ightarrow}{;}coagulation{;}{ ightarrow}{;}pH{;}4$ and the optimum dosage of $FeCl_3$ was $600mg/{ell}$. 2. Proper dosage of $TiO_2$ in the $UV/TiO_2/H_2O_2$ system with pretreatment process was $2g/{ell}$ and $H_2O_2$ was $1000mg/{ell}$, UV contact time was 20min to get $200mg/{ell}$ of $COD_{Cr}$.