The total amount of water resources in China is 2 trillion and 800 billion cubic meters. Among them, 2 trillion and 700 billion cubic meters of surface water and 830 billion cubic meters of underground water, the total number of water resources ranks sixth in the world, and the average per capita volume is 2240 cubic meters, ranking eighty-eighth in 153 countries of the world bank. The current situation of water resources in China is: shortage of total volume, low per capita consumption, uneven distribution of areas, unmatched water and soil resources, increasing water pollution and prominent urban water scarcity. The acceleration of urbanization and the development of regional economy aggravated the burden of local water resources, and also aggravated the pollution of urban groundwater. Many cities had groundwater eutrophication and iron and manganese exceeding standard. Water pollution has become one of the most important restrictive factors in the economic and social development of our country, which has attracted the high attention of the state and local governments. During the "11th Five-Year" period, China has determined that the annual energy consumption per unit GDP will be reduced by 4% and 5 years by 20%. The total emissions of major pollutants, including sulfur dioxide and chemical oxygen demand, will be reduced by 10% in 5 years. In the work of water pollution control, water quality monitoring is an important means of pollution warning, continuous pollutant monitoring and evaluation of treatment effect, which has been attached importance to by relevant departments. As a continuous monitoring tool, water quality on-line monitoring instrument bears the responsibility of providing accurate monitoring data and monitoring reports, and plays an increasingly important role in environmental monitoring.

The traditional environmental water quality monitoring is mainly based on artificial site sampling and laboratory instrument analysis. Although laboratory analysis methods are complete, laboratory monitoring has many defects, such as low monitoring frequency, large sampling error, scattered monitoring data, and can not reflect the change of pollution timely, which is difficult to meet the needs of effective water environment management of government and enterprises. From the development trend and international advanced experience of environmental monitoring abroad, online automatic monitoring of water quality has become an effective way for relevant departments to obtain continuous monitoring data in time. After a few minutes of data collection, the water quality information of the water source can be sent to the server of the environmental analysis center. Once the observed concentration of some pollutants become distorted, environmental regulators can take corresponding measures immediately, concrete analysis of sampling. It can be seen that the greatest advantage of the water quality on-line analysis system is that the water quality monitoring data can be obtained quickly and accurately. The application of automatic water quality monitoring system helps the environmental protection department establish a wide range of monitoring network and collect monitoring data to identify the pollution situation and development trend of the target area. With the development of monitoring technology and instrumentation industry, environmental water quality monitoring has begun to develop in the direction of automation, intelligence and networking.

Throughout the construction of environmental water quality online monitoring system in China, after years of development, a continuous automatic monitoring and management system and technology system with Chinese characteristics has been initially established, and network has been gradually formed.