In order to explore the physiological mechanism and metabolic differences of the green spots ("GrS") formed during the natural air-curing process of cigar tobacco,to improve the appearance quality of wrapper tobacco leaves,and to improve the air-curing technology,the cigar tobacco‘Chuxue 10’was used as an experiment materials,using high-pressure liquid chromatography-tandem mass spectrometry(HPLC-MS/MS) non-targeted metabolomics technology to analyze the metabolic differences between the GrS and normal tissues of tobacco leaves. The results of the study showed that the contents of chlorophyll and chlorogenic acid in GrS were significantly higher than those in normal parts,and a large amount of undecomposed chlorophyll and chlorogenic acid deposited at the end of the drying period was the physiological basis for the formation of GrS. There were significant differences in tyrosine metabolism,phenylalanine metabolism and flavonoid biosynthesis between GrS and normal tissues. Chlorogenic acid and dihydrozeatin can be used as chemical markers in the formation process of GrS,and their content can be detected to monitor whether there will be GrS in the process of air drying. During the yellowing period of tobacco leaves,the humidity in the drying room drops suddenly and the extreme difference is too large,which may be the external environmental factor for the formation of GrS. It is recommended to use the humidity controlled drying room and appropriately increase the humidity in the yellowing period.