The optimal preparation conditions and coagulation/flocculation performance of polymeric phosphate-aluminum chloride (PPAC) were measured. Some parameters such as acid dosage, temperature, reaction time and P/AL molar ratio were investigated. Also, infrared spectroscopy and scattering electron were used to characterize the structure of PPAC. In addition, the coagulation/flocculation process was carried out for wastewater treatment. It is shown that the maximum alumina content is achieved when acid dosage, temperature, time and P/AL molar ratio are 48 ml, 100 ℃, 180 min and 02 respectively; infrared spectroscopy analysis fits well with the product structure; scattering electron analysis suggests a large surface area and a strong condensed state for PPAC; the removal efficiency of 731% and 990% for COD and turbidity respectively are obtained when coagulant dosage, pH value and agitation speed are 032 ml/L, 75~100 and 40 min respectively.