The factors affecting the treatment of oily wastewater with the compound flocculant polyferric sulfate and chitosan were studied by orthogonal experiment.In the experiment, light transmittance, oil content and suspended matter content were selected as test indexes.By means of range analysis of orthogonal experimental results, the order of influence factors such as temperature, PH value, compounding ratio and dosage of flocculant on each index was obtained.After comprehensive analysis, the optimal level combination of each factor was obtained as temperature 50℃, pH 7, inorganic/organic 3:1 and dosage 40mg/L.