GB/T 39388-2020 specifies the method for characterizing the performance of luminometers and luminance meters. The standard specifies the definition and requirements of instrument performance parameters, such as accuracy, Measurement range, etc. Detailed description of various performance testing procedures, including consideration of Light source Stability, uniformity, and measurement operation specifications in different environments. Through this standard, the luminometer and luminance meter performance can be scientifically evaluated, providing a basis for instrument selection, calibrating and mass control, and facilitating accurate measurement in lighting, display and other fields to ensure the accuracy of related Product Research & Development and application.