OBJECTIVE To identify an d analyze chemical cons tituents of Pleione yunnanensis with origin of Pleione yunnanensis. METHODS UPLC-Q-Exactive-Plus-Orbitrap-MS was adopted. The determination was performed on Hyperdil GOLD column with mobile phase consisted of 0.1％ formic acid solution-0.1％ formic acid acetonitrile solution （gradient elution ）at the flow rate of 0.3 mL/min. The column temperature was set at 40 ℃，and sample size was 2 µL. The electrospray ion source was adopted，and the scanning range was m/z 100-1 500，and the scanning mode was positive and negative ion exchange mode of full scan+ddMS2. The structure of chemical constituents were determined by using Compound Discoverer 3.1 software，comparing with mzCloud，PubChem network database and OTCML ，on the basis of reference substance and published literatures. RESULTS & CONCLUSIONS A total of 42 chemical constituents were identified （positive ion mode has 24，negative ion mode has 27）， including 13 benzyl succinate glycosides （such as dactylorhin C ，coelovirin A ，militarine），4 phenol glycosides （such as adenosine ， guanosine，gastrodin），3 alkaloids（choline，betaine，berberine），and one flavonoid （nobiletin），7 aromatics（such as DL-lysine ， DL-arginine，DL-glutamine），one sugar （sucrose），3 benzenes（shancigusin H ，shancigusin H isomer ，batatasin Ⅲ）and 10 others （such as p-methoxybenzoic acid ，monomethyl dodecanedioate ，diphenylamine）. Glucose oxybenzyl and some small mole cules are easy to be lost in the cleavage of benzyl succinate glycosides；glycosyl is easy to be lost in the cleavage of phenol glycosides；the cleavage of alkaloids mainly manifest as the cleavage and loss of small molecular substituents ；demethyla- tion reaction is occurred in most flavonoids.