In this research, ultrasound-assisted aqueous two-phase extraction (UA-ATPE) was utilized to isolate polysaccharides from Siraitia grosvenorii (SGPs). Based on the results of model optimization experiments, the extraction parameters were determined. The total extraction rate of SGPs was 25.77 %, which was 1.39 times higher than that obtained through conventional hot water extraction (HWE). Various analyses indicated that all SGPs were acidic polysaccharides with similar molecular weights. However, there were slight variations in the monosaccharide composition, surface morphology, and infrared spectral characteristics. These structural features endowed SGPs with various antioxidant, hygroscopic, and moisturizing properties, which provided valuable data for the development of the cosmetic raw materials and also presented new ideas for the application of SGPs.