Abstract: OBJECTIVE To clarify the possible mechanism of the compatibility of the root and seed of Cichorium glandulosum. through quantitative and qualitative analysis of the chemical composition before and after compatible. METHODS Ultrasonic extraction method was used to extract 5 samples with the root of Cichorium glandulosum, the seeds of Cichorium glandulosum, and their three ratios(1:2, 1:1, 2:1) for 30 min. Using chicory acid as the external standard, the relative contents of 18 chemical components in each sample were determined by HPLC. By analyzing the molecular weight of the compounds and multistage mass spectrometry fragmentation information provided by UPLC-TQ-MS to identify the characteristic chemical components. RESULTS The types and contents of the chemical components in the samples were changed greatly before and after compatibility, suggesting that the structure of compounds changed after compatibility. Structures of 16 components in five samples were preliminarily speculated by MS spectra. Among them esculine, azelaic acid and 5,8,3¢,4¢-tetrahydroxy-7-methoxylatedflavones were the common components of root and seed of Cichorium glandulosum, chicory acid and quercetin-3-O-glucoside disappeared after compatibility, and chlorogenic acid and esculetin were new compounds after compatibility.CONCLUSION Quantitative and qualitative changes lays a foundation for clarifying compatibility mechanism of the root and seed of Cichorium glandulosum.