Abstract: For the limited carbon source wastewater,biological nitrogen removal process with chemical-aid phosphorus removal can make the effluent meet the nitrogen and phosphorus discharge standards.Attempting to search an effective method of phosphorus removal in the wastewater treatment,we take ferric chloride,aluminum sulfate and ferrous sulfite to do beaker experiment.The following conclusions can be drawn that phosphorus removal efficiency of ferric chloride is higher than that of aluminum sulfate and ferrous sulfite.All of the flocculants can bring down the acidity of wastewater and ferrous sulfite can reduce the DO level of wastewater with the same dosing condition.Considering efficiency and operation cost,ferrous sulfite is adopted as flocculants.When the dosing of ferrous sulfite is 35 mg/L,the ρ(TP) removal efficiency can reach 93%,the effluent ρ(TP) concentration is 0.45 mg/L.After dosing ferrous sulfite,the active sludge concentration of aeration tank was increased,sludge sedimentation performance was strengthened,and SVI decreased.