Polyacrylamide and polymeric aluminum chloride are commonly used in wastewater treatment, their function is to reduce the suspended solids in the wastewater. The dosing quantity of polyacrylamide and polymeric aluminum chloride and the treatment effect on wastewater were studied. The results show that in wastewater treatment, when polyacrylamide and polymeric aluminum chloride as flocculant are added, the adding amount should be determined according to the actual situation of the wastewater, and the treatment effect is not good with the increase of adding amount of flocculant. At the same time, adding appropriate amount of flocculant can remove part of COD and avoid the increase of COD in the wastewater because of adding excessive flocculant.