Abstract: To explore the preponderance of vacuum extraction in the extraction of Polygonum cuspidatum,we determined the optimal conditions for its vacuum extraction with resveratrol as an investigation subject. We compared its extraction rate, extract yield, light transmittance, protein content, soluble sugar content and DPPH free radical scavenging rate of resveratrol with heat reflux extraction, ultrasonic extraction and warm immersion extraction. We discover its optimal conditions are ethanol concentration of 70%, solid to liquid ratio of 1:10, vacuum degree of 0.02 MPa, temperature of 50 ℃, and extraction time of 1 hour. Vacuum extraction has higher resveratrol yield, transmittance and DPPH radical scavenging rates and lower extract yield, protein, soluble sugar and other impurities contents, as compared with heat reflux and ultrasonic extraction methods. Results show that it is superior to other extraction methods, especially for thermosensitive components included traditional Chinese medicines.

Key words: vacuum extraction, resveratrol, DPPH, Polygonum cuspidatum