OBJECTIVE： To optimize the extraction technology of volatile oil from Guizhou Piper puberulum and analyze its chemical compositions. METHODS： The volatile oil was extracted from Guizhou P. puberulum by steam distillation （HD method）. Orthogonal test was designed using the extract rate of volatile oil as index， with soaking time， extraction time， material-liquid ratio   （g/ml） and smashed particle size as factors. Validation test was also conducted. GC-MS was adopted to separate and identify the chemical compositions of the volatile oil from Guizhou P. puberulum， and area normalization method was used for the determination of relative percentage of each composition. RESULTS： The optimal extraction technology was as follows as soaking time of 3 h， extraction time of 5 h， material-liquid ratio of 1 ∶ 10 and degree of grinding 12 meshes； in validation test， average extract rate of volatile oil was 59.83％（RSD＝0.905 3％，n＝3）. 78 compounds were identified， and relative percentage was 81.125％； there were four main compositions such as γ-elemene （11.858％）， 4-vinyl-α， 4-trimethyl-3-（1-methylvinyl）-cyclohexane methanol（8.701％）， carnation （8.443％） and α-caryophyllene （6.216％）. CONCLUSIONS： Optimized HD method is simple in production equipment， low in production cost， good in repeatability； determination method of validation oil is simple and feasible， and can analyze chemical compositions of volatile oil from Guizhou P. puberulum.