This standard specifies the technical requirements, performance indicators and detection methods of the chemical oxygen demand (CODa) water quality online automatic monitor, which is suitable for the monitoring of surface water, domestic sewage and industrial wastewater. The range of the instrument should include 15~ 2000 mg/L [p (CI) ≤ 2000 mg/L], which can meet various water quality monitoring needs. A series of normative documents are quoted, including the general provisions of the instruction manual for industrial products, the data transmission standard for the online monitoring system of pollutants, and the determination method of the chemical oxygen demand for water quality. The terms and definitions cover the basic detection range, extended detection range, sample, error of indication, etc.