To provide a theoretical basis for revealing the relationship between ultraweak luminescence (UWL) and plant growth physiology and the source of UWL production in plants. In this experiment, Cerasus humilis was used as the test material and conducted an indoor potted experiment with different concentrations of salt stress treatment to study the change rule and correlation of chloroplast structure and function (chlorophyll metabolism, photosystem activity, photosynthetic performance and energy level) and UWL of Cerasus humilis leaves under salt stress. Results show that: (1) salt stress reduced the UWL intensity of Cerasus humilis leaves, and the higher the salt concentration, the greater the decrease in UWL strength. (2) Salt stress destroyed the chloroplast structure of Cerasus humilis leaf and reduced its function. The decrease in chloroplast function includes a significant decrease in the content of the main precursor substances for chlorophyll synthesis (ALA, Mg-ProtoⅨ),, and the activity of chlorophyll-degrading enzyme chlorophyll enzyme (Chlase) significant increased, resulting in a significant decrease in chlorophyll congtent (Chla, Chlb, Car and Chla+b). At the same time, the FV/Fm, FV/FO, PIABS, RC/CSm, φE0 and ΨE0 of the leaves of Cerasus humilis decreased rapidly, and the activity of photosystem II was severely inhibited. Make further decrease on the Pn, Tr, and Gs, while Ci increase simultaneously, resulting in a significant decrease in photosynthetic performance. The significant decrease in ATP content and EC lead to an overall decrease in energy levels. (3) UWL intensity of Cerasus humilis leaves and their chlorophyll synthesis precursors and chlorophyll content (ALA、Mg-ProtoⅨ、Chla、Chlb、Car and Chla+b), photosystem II activity (FV/Fm、FV/FO、PIABS、RC/CSm、φE0、ΨE0), photosynthetic performance (Pn、Tr、Gs) and energy level (ATP、EC) all showed significant or extremely significant positive correlations. (4) The higher the salt concentration, the longer the stress time, and the greater the degree of changes in the UWL intensity and chloroplast function indicators of Cerasus humilis leaves, and the overall correlation under high-concentration salt treatment is higher than that under low-concentration salt treatment. In summary, under salt stress conditions, the chloroplast structure of Cerasus humilis leaves is destroyed, while its function is damaged and its vitality decreases, resulting in a decrease in UWL intensity. The intensity of UWL is closely related to chloroplasts and their functions, and chloroplasts may be one of the organelles of UWL. The UWL intensity can be used to reflect the degree of salt stress damage to the leaves of Cerasus humilis.