In this paper,the leaching of magnolol in Magnolia officinalis Rehd et Wils by power ultrasound was studied with respect to the effects of different ultrasound frequency and leaching time.Experimental results show that more magnolol can be acquired when the ultrasound frequency is 20 kHz and the leaching time is over 10 minutes.The leaching by power ultrasound has shorter leaching time, higher yield than cold leaching method and supercritical fluid extraction (SFE) method.