Objective To analyze the chemical constituents of essential oil extracted from Apocynum venetum and screen the index components to evaluate essential oil in samples from different habitats. Methods Head-space-GC／MS was employed to prepare essential oil from Apocynum venetum，with HP-5 quartz capillary column，extraction temperature 90℃ ，hold 30 min，injection volume 1．5 mL .The datas were disposed by multivariate statistical analysis to screen the index components. Result 80 volatile components were analyzed and quantified. The system reproducibility was good .7 index volatile components were screened and the total content of the index components in samples from Jiangsu is higher than others. Conclusion The total contents of the index components were distinct in Apocynum venetum from different habitats. A rapid，simple and reliable method using HS-GC/MS and multivariate statistical methed was developed to analyze the volatile components which can be an alternative for quality evaluation for TCMs such as Apocynum venetum．