Abstract: Citrus medica L. var. sarcodactylis Swingle is an important and widely used herbal medicine, which has been used in China for thousands of years, and has effects of antitumor, immunomodulatory, antioxidative, anti-inflammatory, hypoglycemic, hypolipidemic and antitussive. The processed Citrus medica L. var. sarcodactylis Swingle (PCM), as Lingnan characteristic traditional Chinese sliced herbal medicine, has similar effects but less pungent, is more popular than the raw products in the Lingnan area, especially in Guangdong Provence. The technique of ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS) is widely and effectively used for the identification of chemical components from traditional Chinese medicine, which is considered as a forceful analysis technology in this field due to its rapid separation, accurate mass measurement and tandem mass spectrometry. In this study, UPLC-Q-TOF MS technology was used to analyze and identify the chemical components of PCM. The sample was extracted by methanol and the chromatographic separation was performed on a Poroshell 120 EC-C18 column (3.0 mm×150 mm×2.7 μm）. The mobile phase was consisted of eluent A (0.1% formic acid and 5 mmol/L ammonium acetate in water) and eluent B (acetonitrile) with the flow rate of 0.35 mL/min. The column temperature was 30 ℃, the chamber temperature was 25 ℃, and the injection volume was 6 μL at negative mode and 4 μL at positive mode, respectively. Electrospray ionization (ESI) was applied for scanning under positive and negative ion modes with the scanning range of m/z 100-1 000. The main chromatographic peaks in the total ion chromatogram (TIC) were characterized at positive and negative ion modes. Based on accurate mass, fragment ions, retention behaviors, previous reports, network database, reference standards and fragmentation pathways of compounds, a total of 67 components were identified, including 12 flavonoids and flavonoid glycosides, 20 coumarins, 15 organic acids, 6 glycosides, 5 limonin, and 7 other compounds. 24 compounds were first discovered from Citrus medica L. var. sarcodactylis Swingle, including quinic acid, malic acid, citric acid, protocatechuic acid, sucrose, catechol, esculetol, luteolin-6, 8-di-C-glucosid, 4-hydroxybenzaldehyde, eriocidin, chrysoeriol-6, 8-di-C-glucoside, diosmetin-6-C-glucoside, p-hydroxycinnamic acid, scopoletin and its isomers, azelaic acid, isofraxidin and its isomers, deacetylnomilinic acid, nomilinic acid, heraclenin, ricinoleic acid, (E, E)-9-oxooctadeca-10, 12-dienoic acid. This method is suitable for the rapid detection of compounds for PCM with easy operation, high sensitivity and excellent precision. The chemical substances of PCM were comprehensively clarified. The result provides valuable information for its quality control and pharmacological application.