Abstract: Pu-erh teas with different storage year as the research objects, national standard analysis method and Gas Chromatograph-Mass Spectrometer ( GC/MS) were adopted to study their physical and chemical quality and characteristics Chenxiang material basis.Results showed that with the increase of storage period, content of water extract and soluble sugar in pu-erh teas were first decreased and then increased. Tea polyphenols and catechins, amino acid showed decreased trend in general.Other quality composition did not change significantly. This research identified 54 aroma compounds including the alcohols, ketones, methoxy compounds, aldehydes and alkenes, etc. Compounds with ‘Chenxiang ' characteristics such as pleasant wood and medicine fragrant were increased significantly compared with the contrast, mainly including Cedrol, Cedrene, β-guaiene, α-Ionone, β-Ionone, Dihydroactinidiolide, Benzoic acid benzyl ester, Acetic acid benzyl ester etc., however substances with flowery scent such as Linalool, Methyl Salicylate and Nonanal etc. showed the tendency of decrease.This research deduced that in old pu-erh teas the material basis of characteristic‘Chenxiang'was mainly the above aromatic substances with pleasant wood and medicine smell.