Objective:The cell crusher-assisted hot water extraction and antioxidant activity of mulberry polysaccharide were investigated. Methods:Extraction time, solid-liquid ratio, ultrasonic time, ultrasonic power and extraction temperature were used as the test conditions, the optimum extraction conditions of mulberry polysaccharide were investigated by four factors and three levels of orthogonal test. The antioxidant capacity of mulberry polysaccharide was determined by comparing the scavenging rates of VC and mulberry polysaccharide to DPPH· and hydroxyl radical (·OH). Results: The results showed that the highest yield of mulberry polysaccharide was (6.63±0.07)%, when the extraction time was 30 min,the ultrasonic power was 160 W, the ultrasonic time was 12.5 min, the solid-liquid ratio was 1∶30 (g/mL), and the extraction temperature was 30 ℃. In the scavenging test of DPPH· and ·OH, mulberry polysaccharide concentration was positively correlated with the clearance rate, and the scavenging ability of ·OH was (76.21±2.21)%. In the comparison test with the antioxidant capacity of VC, the results showed that the antioxidant capacity of VC was better than that of mulberry polysaccharide. Conclusion: Ultrasonic cell crusher-assisted extraction is beneficial to the extraction of mulberry polysaccharide.