Beneficiation reagents exist in a great variety, with high toxicity and complex material structure, and it is difficult to be used by microorganisms quickly and efficiently. They can stay for a long time after they go into the environment. It is difficult to guarantee the organic flotation reagents in the water to discharge down into standard values and to be steady for a long time by physical and chemical methods. So, it is imperative to recycle the beneficiation wastewater and to achieve the drainage standard by biological methods. The Anaerobic-Aerobic reactor starts by using the method of gradually increasing the floating agent concentration and fixing the hydraulic retention time. The treatment efficiencies of COD and floating agent and the changes of biofacies are analyzed. The results show that during the biofilm formation and the domestication, the removal rate of COD is mainly concentrated in the aerobic reactor. Anaerobic reactor has also a certain removal effect, but far below that of an aerobic reactor. 40 days after a reactor starts, the total removal rate of COD is stable at a level of 55% and the total removal rates of aniline aerofloat, diethyldithiocarbamate and butyl xanthate reach 92%, 84% and 82%, the biofacies are steady and the biofilm is formed successfully.