The invention relates to the field of piperaquine phosphate impurity control, and specifically relates to a control method of piperaquine phosphate impurity. The control method of piperaquine phosphate impurity comprises the following steps: 1), adding a non-polar solvent into a piperaquine phosphate crude product, stirring and filtering; 2), adding a polar solvent, conducting reflux, stirring and filtering; 3), adding a water / polar mixed solvent, stirring and dissolving at 90-110 DEG, adding activated carbon for decoloring and filtering to obtain a filtrate, cooling, crystallizing, filtering, washing and drying. The steps 1) 2) and 3) are not in a particular order. The control method of piperaquine phosphate impurity provided by the invention has the advantages of simple process, and extensive equipment and reagent sources, thus indirectly reducing cost for drug impurity removal, and can be widely applied to preparation of piperaquine phosphate.