Abstract: A new flocculant named polymerized silicon-phosphorus ferric sulfate was developed in lab to treat high-viscosity petrochemical wastewater in a plant of Liaohe Pertrochemical Corporation. The results showed that its optimal treating parameters are as follows: mass concentration 200 mg/L, pH value 6~9, temperature range 25~45°C, stirring time 2 min and sedimentating time 3 min. Under such conditions, a series of comparison tests were done between the newly-developed flocculant and currently-used one during wastewater treatment in the plant, and the comparison results showed that the former can remove 94.1% oil, 69.4% COD, 88.9% sulfide and 43.5% volatile phenol, i.e., much higher than the latter of which the corresponding removing rates are 80.5%, 35.8%, 21.1% and 17.3%, respectively.