The ultrasound-assisted method was used to extract isorhamnetin from marc of the Hippophae rhamnoides fruits. A single factor experiment was conducted to select ideal ultrasonic frequency, extraction time and frequency, extraction temperature, solid-liquid ratio, and extraction solvent. These extraction conditions were then verified with an orthogonal experiment. The best conditions of the ultrasonic method for isorhamnetin extraction from Hippophae rhamnoides marc were: the ultrasonic frequency of 40 kHz, the extraction temperature of 50 ℃, V _{ethyl acetate}: V_{95% ethyl alcohol} of 4:6 as the extraction solvent, two extractions with one hour each, and the solid-liquid of 1:25. Under these conditions, the yield of isorhamnetin extraction can reach 5.09 mg·g^-1.