Objective To study the optimum conditions for extracting total flavonoids from Acanthus illicifolius through the two extraction processes.Methods An orthogonal test of L_9 (3~4)was designed to select optimum operation conditions for extracting total flavonoids from Acanthus illicifolius through Soxhelt and ultrasonic extraction process.According to the output of total flavonoids under the different extraction conditions,which were selected as ethanol contents,extraction temperatures and extraction time for Soxhelt extraction process, and extraction time,ethanol contents and ratio of liquid to material for ultrasonic extraction process.Results The optimum conditions were established as follows:ethanol content 60%, extraction temperature 85℃and extraction time 2.5h in Soxhlet extraction process;Ethanol content 50%,extraction time 50min,ratio of liquid to material 40:1 in ultrasonic extraction process.The extraction temperature was the main factor on the Soxhlet extraction process, and the ethanol content on the ultrasonic extraction process.Conclusion The technology of ultrasonic extraction is better than that of Soxhlet extraction to extract the total flavonoids from Acanthus illicifolius.The max output of total flavonoid from Acanthus illicifolius can reach to 3.82%.