Abstract: Effects of phosphorus removal by three kinds of composite polyaluminum chloride(PAC)in laboratory scale are compared in this article.Relations between phosphorus removal and turbidity removal by coagulation are investigated.Effects of water temperature and pH value to phosphorus removal are observed,and removal effects of various phosphorus formations by coagulation are reviewed.Effects of phosphorus removal are further studied by combined applications of PAC and polyacrylamide(PAM).The results showed that the No.3 PAC is the most effective one,and effects of phosphorus removal of drinking water treatment can be clearly improved by enhanced coagulation.The optimum pH value of phosphorus removal is 7.Effects of phosphorus removal can be improved by raising water temperature.In general,it is more difficult to remove dissolved phosphorus,but phosphate can be effectively removed by dosing more coagulant.The effects of phosphorus removal by coagulation aid can be achieved more effectively by adding PAM after five minutes medium rate mixing during coagulation,with the optimum dosage of 0.7mg/L.