This invention relates to a method of extracting crude polysaccharide by microwave-assisted from Artemisia sphaerocephala seed de-oiling dregs. In particular, the invention comprising: microwave-assisted extraction, enzymatic hydrolysis, dialysis et. al. It provides a technique whereby the polysaccharide can be extracted effectively, in a relatively short period of time (20-30 min) with respect to conventional extraction methods and allows for an enhanced extraction yield (more than 30%). Furthermore, the invention also allows for the extraction of material with less solvent consumption, good reproducibility, excellent solubility, energy conservation, environmental protection, and showed great potential for efficient sample preparation and large-scale industrial application in the near future. With great resource advantage of Artemisia sphaerocephala in China, the invention has bright perspectives in promoting local economic development.