Abstract: To optimize the ultrasound-assisted three-phase partitioning for the simultaneous extraction of allicin and polysaccharides from garlic. The effect of polyethylene glycol (PEG) concentration, ammonium sulfate concentration, sonication temperature, and sonication time on the extraction efficiency of allicin and polysaccharides were investigated, respectively. The simultaneous extraction process conditions of allicin and polysaccharides were optimized according to the Box-Behnken experimental design. Results showed that the optimal conditions were PEG concentration of 24%, the ultrasonic temperature of 34 °C, and ultrasonic time of 50 min. Under these conditions, the extraction efficiency of allicin and polysaccharide was calculated according to the anhydrous calculation, reaching 3.564 and 43.86 mg/g, respectively. The optimized extraction process could effectively and simultaneously extract allicin and polysaccharides from garlic, which would provide a foundation for the deep research, development, and application of functional products from natural garlic.