Objective:To study the volatile oil composition differences from Four of Cyperus rotundus of Jianchangbang and raw materials of Cyperus rotundus

and discuss the influence of Jianchangbang processing method on the volatile components. Method: The comparative analysis was performed with HPLC and GC-MS on the constituents of volatile oil of Rhizoma Cyperi before and after processing. Result: the HPLC method showed that the principal component of Four of Cyperus rotundus and raw materials Rhizoma Cyperi (relative peak area of more than 10%) had no significant differences (including 3). The relative peak area of main component was slightly different. The results of GC-MS detection showed that Four of Cyperus rotundusand health products of Rhizoma Cyperi contained a number of different compounds. 33 kinds of compounds of volatile oil extract from Rhizoma Cyperi raw materials were distinguished

and 41 kinds of compounds were distinguished from Four of Cyperus rotundus volatile oil extract. But the main components had no obvious difference. The relative peak area of principal component from volatile oil by preparation method was in overall downward trend. Conclusion: 20 components of volatile oil extracts from Four of Cyperus rotundus are increased compared with crude volatile oil extracts of Cyperus rotundus

but the relative peak areas of principal component are comparatively different. HPLC method and GC-MS analysis get the consistent results.