Abstract: Preparition technology of poly aluminum chloride with aluminum dregs as raw material was studied.Effects of reaction temperature，reaction time，hydrochloric acid concentration，and ratio of liquid to solid（volume/mass ratio of HCl to aluminum dregs） on the leaching rate of alumina were studied by single factor analysis method.Based on single factor experiment，the orthogonal experiment design was used to optimize the preparation conditions.The optimal preparation conditions were as follows:reaction temperature was 90 ℃， reaction time was 30 min，hydrochloric acid concentration was 8 mol/L，and ratio of liquid to solid was 1.5 mL/g.Under these conditions，the leaching rate of alumina was 13.01%.Wastewater in middle course of papermaking had been treated by self-made poly aluminum chloride and the result of the experiment was satisfactory.

Key words: aluminum dregs, poly aluminum chloride, aluminum formation product factory