In order to determine the optimal extraction process for the essential oil of Yuexi small yellow ginger,investigate the effects of different extraction methods on the yield and microstructure of small yellow ginger essential oil,and establish a GC-MS detection method for the volatile substances of Yuexi small yellow ginger.In this study,steam distillation,ultrasonic-assisted steam distillation,ultrasonic-microwave synergistic assisted steam distillation and ultrasound-enzyme synergistic assisted steam distillation were used to extract the essential oil.The essential oil yields of each method were compared,and the method with the highest yield was selected to determine the optimal extraction process by one-way test and orthogonal optimization.The results showed that the highest yield of essential oils was obtained by ultrasound-enzyme synergistic assisted steam distillation and the optimal extraction process was as follows:soild-liquid ratio of 1∶3.5 (g/mL),ultrasonic temperature of 50 ℃,ultrasonic power of 400 W,ultrasonic time of 20 min,compound enzyme dosage (hemicellulase∶β-glucosidase=1∶1) 40 U/g,the enzymolysis temperature is 40 ℃,the pH of the enzyme is 5.5,the enzymolysis time is 2 h,and the extraction time is 45 min.Under these conditions,the yield of essential oil is 3.28%.Scanning electron microscopy of ginger pomace after essential oil extraction revealed that the cellular integrity of ginger pomace obtained by ultrasound-enzyme synergistic assisted steam distillation was the most severely disrupted,This indicates that the method is more thorough in the extraction of essential oils.A total of 75 volatile substances were extracted and identified from fresh ginger by headspace solid-phase microextraction (HS-SPME) extraction and ultrasound-enzyme synergistic assisted steam distillation,Among them,49 species were identified by HS-SPME extraction,and 60 species were identified by ultrasound-enzyme synergistic assisted steam distillation.This study provides a new idea for the extraction of essential oils from small yellow ginger,and provides a reference basis for the deep processing and utilization of ginger.