Abstract: Open experiment plays an important role in improving students'experimental skill and cultivating students'innovation ability. In the Open experiment,this paper guides students to expand the research on the use of waste aluminum foil to prepare polyalkali aluminum chloride in the in-class experiment. Based on the analysis of teaching materials and preparation scheme of the literature,an improved preparation scheme is proposed. The three preparation scheme were analyzed and compared from the preparation effect. Using a variety of experimental methods to complete the same experiment is conducive to stimulate students'interest,developing students'ideas,and further improving students'practical ability and innovative ability.