Abstract: The recycling of the waste liquid of the experiment can reduce the environmental pollution and save the funds of the experiment teaching.Based on the existing conditions of the laboratory,this paper designed two opening experiments for undergraduates according to the chromium and iodine containing wastewater produced in the experiments.It analyzed the preparation of potassium dichromate by chromium containing wastewater,the experimental principle and procedure for preparing iodine with iodine containing waste in details.It summarized the implementation,organization and evaluation of the two kinds of waste liquid recycling experiments,as well as the problems that should be paid attention to in the course of opening experiment teaching.Generally speaking,these open experiments are helpful to improve students' practical ability and the ability to solve practical problems by using the analytical method.