The JJG 2029-2006 standard specifies the verification of colorimeters on the surface of objects to ensure the accuracy and conformity of the colorimeter. The standard defines a national reference for chroma units, including basic Measurement appliances and parameters, and how to transfer color measurements to work Measurement appliances through working benchmarks and standard Measurement appliances. Colorimeters are divided into surface color Measurement and Light source color Measurement. This standard mainly deals with surface color Measurement. The chroma national reference is used to reproduce colorimeter units, including chroma reference devices and whiteboards, to achieve absolute measurement of the Light spectrum reflection factor. The measurement is based on the International Commission on Illumination (CIE) standard illuminator and standard chroma observer, using 0/d conditions for chroma measurement to ensure the conformity and accuracy of the national color metric.