With the strengthening of urbanization in China, the reconstruction of big cities and the expansion of small and medium-sized cities are getting faster and faster. The pollution of water resources is becoming more and more serious, which directly threatens people's drinking water safety and seriously damages the overall environment and landscape of the city. Our government's investment in sewage treatment construction is gradually increasing, and the effluent water quality index requirements of sewage plants are more and more strict, which requires that the sewage treatment system operates more stably and the effluent water quality meets the standard rate is improved. Sewage contains large amounts of organic matter, nitrogen, phosphorus and other inorganic salt, the degradation of the pollutants removal mainly completed in the biochemical pool, biochemical processes of temperature, pH, ORP, dissolved oxygen, sludge concentration is particularly important to the water quality parameters, such as, directly affects the activity of microorganism, which affect the sewage treatment effect, so in the process of sewage treatment for the real-time online monitoring of water quality parameters, mastery of timely, accurate and effective wastewater treatment situation and respond plays a vital role.