Standard JJF 1907-2021 specifies the calibration procedure for Gas Analyzers for on-line monitoring of environment air. The standard is applicable to Gas Analyzers for on-line monitoring of nitrogen dioxide, sulfur dioxide, ozone and carbon monoxide in the measurement environment air, covering the Measurement range of SO2, NO2, O3 and CO. The detection principle includes chemiluminescence, ultraviolet fluorescence, ultraviolet absorption, non-dispersed infrared absorption and gas filter correlated infrared absorption. Light spectrum analysis methods such as inhalation Sampling method are used. The instrument consists of a sampling unit, a detection unit, a signal processing unit and a display unit. Optical inspection sensor module converts the sampled environment air into electrical signals, and then processes and outputs the concentration data through electronic circuits. The implementation of this standard ensures the accuracy and Reliability of environment air mass monitoring equipment under various working conditions, and supports environment protection and public safety management.