Abstract: In order to construct an appropriate ultrasonic-assisted acid hydrolysis method for pectin from pumpkin, we conducted the single-factor test including the extraction solution acidity, the ratio of material to liquid (g/mL), extraction temperature and extraction time. The L9（34）orthogonal test was used to optimize the conditions for ultrasonic-assisted acid hydrolysis method. The result showed that the optimization ultrasonic-assisted acid hydrolysis conditions were extraction pH value 2.0, ratio of solid to liquid (g/mL) 1:30, extraction temperature 75 ℃, extraction time 60min, and the output ratio of pumpkin pectin of 21.9% was obtained at the optimum conditions.