Acanthopanax Senticosus is a traditional medicinal plant in China. Flavonoids are one of the main active ingredients of this plant. Four extraction technologies of flavonoids from Acanthopanax Senticosus were investigated and compared, including microwave-assisted extraction, ultrasonic extraction, reflux extraction and Soxhlet extraction. The results showed that microwave-assisted extraction was most suitable for the extraction of flavonoids from Acanthopanax Senticosus because of its high effect and short extraction time. The found optimum extraction conditions were that the ethanol concentration was 50% (v/v), solid–liquid ratio was 1:50, extraction temperature was 50°C and irradiation time was 9 min. Quantification was performed by means of UV–Vis spectrophotometry with chromogenic system of NaNO2–Al (NO3)3–NaOH. Under the optimum conditions, the calibration curve for the analyte was linear with the correlation coefficients greater than 0.9999. The average recovery was 101.8%, and its RSD was 0.87%(n=5). The total content of flavonoids was18.72 mg g−1.