In this study, the microwave extraction of polysaccharides from the polysaccharides was studied, and the optimal conditions for microwave extraction of polysaccharides from the polysaccharides were determined. The microwaves were 500 W, the extraction temperature was 90 °C, the extraction time was 15 min, and the extraction was performed twice. The yield of polysaccharide was 11.38%. This is close to the calculation results of the response surface model equation, indicating that the experimental conditions are reasonable, which can provide a theoretical basis for the large-scale production of Brassica polysaccharide. However, the crude polysaccharide obtained by the extraction contains 31.34% polysaccharide, and contains more impurities, which can be purified by removing protein or chromatography to improve the purity of the polysaccharide and determine the structure of the polysaccharide. High-value applications are of great significance.