[Objective] To optimize the ultrasonic extraction conditions of tannins from Rhodiola crenulata(Hook.f.et Thoms.)H.Ohba.[Method] The extraction conditions were optimized by orthogonal test based on single factor test,and the content of tannins was determined with casein method.[Result] The optimal extraction conditions for tannins from Rhodiola crenulata(Hook.f.et Thoms.)H.Ohba.were determined to be: extraction solvent of 70% acetone,solid-to-liquid ratio of 1∶10,ultrasonic power of 450 W and extraction dur...