The extracting variables of UAHE were optimized through RSM and the optimized conditions were power intensity of 12.56 W/cm2, extraction temperature of 66.71 °C, and sonication time of 27.95 min. A comprehensive comparison carried out between UAHE and CHE showed that UAHE provided higher pectin yield with lower temperature and shorter extraction time. Besides, although the chemical structure was not influenced by different extraction methods, the color, microstructure, physico-chemical properties and primary structure of UP were significantly different from those of CP. The results demonstrated that UAHE was an efficient and economic technique for extracting pectin from plant resources. Pectin produced by this novel method was preliminarily modified, and could be further processed to be modified pectin in order to improve its bioactivities.