Flame diagnosis technology refers to the use of spectrum, image, noise and other sensing means to obtain flame state and other information, through the obtained information to analyze the combustion and gasification state of flame. The development of combustion process diagnosis and optimizing diagnosis methods is one of the challenges facing the combustion industry. The improvement of combustion diagnosis technology can enhance the monitoring of efficiency, reliability and flexibility of different fuels. The flame spectrum diagnosis can determine the position of the flame and the equivalence ratio etc. Flame spectral diagnosis can also explore the characteristics of flame, such as instantaneous species etc. A comprehensive understanding of the combustion process can be achieved by means of spectral diagnosis. Due to the laser diagnosis method has the characteristics of a complex system and strict environmental requirements, chemiluminescence-based detection methods are getting more and more attention. The purpose of this paper is to describe the research progress and development trend of chemiluminescence. It mainly introduced the generation mechanism of chemiluminescence, Chemiluminescence reaction mechanism model and main production rate of intermediate combustion products (OH^* , CH^* and C₂^*). Meanwhile, it summarized the application of flame spectrum diagnosis technology in the research of intermediate combustion products. Chemiluminescence can be used to reflect the heat release rate. Chemiluminescence peak intensities can be used to indicate the peak position of temperature. The relationship between the peak intensity of chemiluminescence and the equivalent ratio is briefly reviewed. Chemiluminescence can be used to indicate the height of lift-off flame, and the flame structure characterization based on the image processing is reviewed. The application of chemiluminescence as a diagnostic tool is affected in flames containing additional background radiation and the measurement of CH^* chemiluminescence will also be obscured by the black body radiation are also discussed. The application prospect of flame spectrum diagnosis technology in the future has further prospected. More detailed combustion reaction mechanisms are needed to be revealed. The effect of turbulence on combustion needs to be reduced. Soot affects the accuracy of the flame image is needed to be reduced and the accuracy of cameras and spectrometers are needed to be improved in the future. The on-line measurement methods of image and techniques of chemiluminescence spectroscopy have important scientific development significance and broad engineering guidance significance for promoting the research in the fields related to combustion and flow.