Objective: To analyse and identify the chemical components between old leaves and young leaves of Cyclocandra paliurus

and compare the category and contents of components between the old leaves and young leaves. Method: The main chemical components in 50% methanol extract from old leaves and young leaves of C. paliurus were analyzed and identified by ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS/MS). The contents of chlorogenic acid

kaempferol

isoquercitrin

quercitrin and quercetin of C. paliurus were determined by high performance liquid chromatography on an Inter Sustain-C18(4.6 mm×250 mm

5 μm) with acetonitrile-0.1% formic acid as mobile phase for gradient elution at a flow rate of 1.0 mL·min-1

and the detection wavelength was set at 254 nm and the column temperature at 30℃.Then the results were analyzed by using principal component analysis. Result: We finally identified 30 compounds from old leaves and young leaves. There were 21 common components among the two types of leaves. 2 components were only in young leaves

while 7 components were only in old leaves. There were quantitative differences in the contents of five components between old leaves and young leaves. 15 samples were divided into two main groups by principal component analysis. One was old leaves and the other was young leaves. Conclusion: The main chemical components in old leaves and young leaves of C. paliurus were basically similar. Comparatively

the chemical componentsin the old leaves were more abundant and the contents of five components were higher than thosein young ones. The established method could be used to betteridentify the chemical components in the leaves of C. paliurus

and distinguish the old leaves and young leaves

providing a reference for its quality control based on leaves of C. paliurus.