Drinking water source has been polluted in different degrees in China and most of the drinking water sources belongs to the III class and above class. The conventional treatment process includes flocculation--sedimentation--filtration--disinfection process is difficult to meet the new standard of drinking water. Municipal water advanced treatment uses the process of ozone - biological activated carbon. Ozone strong oxidation ability could achieve decomposition of organic pollutants, improve the degradation of activated carbon to organic matter, effectively kill bacteria and viruses, reduce by products and reduce the odor and iron, manganese, etc. so that it could improve the quality of water, taste. This treatment process has become the main technology in Chinese municipal water treatment.