The purpose of this study determines the optimal extraction conditions of Polygonum multiflorum Thunb root using microwave assisted extraction method (MAE) at microwave power of 127 W and response surface methodology (RSM). Extraction process consists of three independent factors: acetone concentration (X₁:50-70%), solvent/material ratio (X₂): 30/1-50/1 (v/w) and extraction time (X₃: 3-7 minutes) which were optimized by two responses including the total polyphenol content (TPC) and antioxidant capacity (AC). They were determined by Folin Ciocalteu method and free radical scavening activity method, respectively with gallic acid, Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic  acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) as standard reagents. The optimal extraction conditions were found to be acetone concentration (X₁) of 57.35 %, solvent/material ratio (X₂) of 39.98/1 and extraction time (X₃) of 4.82 minutes. Under this optimal condition, TPC and AC were in agreement with the experimental values, thus indicating suitability of RSM in optimizing the extraction conditions. Some types of phenolic compounds such as anthraquinones, tannins and flavonoids compounds were found in the root extracts. This research can be useful in the pharmaceutical and food industry in studying the extraction process of bioactive compounds as phenolic compounds from this plants.