The optimum process for the separation and purification of Al 1 3 was investigated in detail in this paper. The various influencing factors were discussed. The experimental results show that the concentration and basicity (B, OH/Al ratio) of polyaluminum chloride (PACl), Al/SO 4 ratio, Ba/SO 4 ratio and ultrasonic reaction have different roles in the separation and purification of Al 1 3 . Moderate concentration of PACl with the basicity around 2.0 gives some benefits in the separation of Al 1 3 . An optimization condition has then been found to obtain high purity Al 1 3 by involving Al/SO 4 and Ba/SO 4 ratios of 1:1, and 3h ultrasonic time. Further indication on the separation of Al 1 3 is also discussed.