The wastewater treatment process of a tannery is converted int o dyeing wastewater treatment process, and debugged. A new type of liquid PAC, which is produced in a plant in Xiaoshan,is used for debugging. The treatment efficiency is better than that of ferrous sulfate, the average removal rate of COD_Cr is up to 61.78%. It also indicates that such a simple coagulation - aer obic treatment can ensure the dyeing wastewater to meet the requirement of the discharge standard. So, this reformation is feasible.