The optimum conditions of ultrasonic extraction of total triterpenoid from leaves of Alisma orientalis (Sam.) Juzep. were investigated in this study. On the basis of single factor experiments, with yields of total triterpenoid as indexes, the three levels of four factors of Box-Behnken experimental design and response surface methodology was adopted to optimize extraction conditions by taking extraction temperature ,ethanol concentration, extraction time and the ratio of material to solvent as factors. Results: Optimal extraction technology was as following, i.e. the ethanol concentration of 70%, the extracting for 46.00 min at 57.00 ℃, and the ratio of material to solvent was 114 (g/mL), ultrasonic time for 30 min. Then the total triterpenes extraction rate reached 2.98% in this condition.