Abstract: In the present study, the effect of microwave irradiation on the extraction process of polysaccharides was analyzed from principal component analysis (PCA), which in order to explore whether microwave extraction affected structural characteristics of the polysaccharide product. Monosaccharide composition of Artemisia sphaerocephala polysaccharides (ASP) was detected, which were obtained under different microwave extraction conditions. It was showed that ASP was composed of L-arabinose, D-xylose, D-lyxose, D-mannose, D-glucose and D-galactose (molar ratio of 1:4.98:1.69:27.86:3.76:13.92), of which mannose and galactose were the main monosaccharides. The result indicated that the change of microwave extraction conditions had an obvious effect on the content of main monosaccharide in ASP. Meanwhile, microwave extraction time and temperature were positively correlated with main monosaccharide content, while microwave extraction power was opposite. Among them, the effect of microwave extraction time was the most significant, and the optimum microwave extraction conditions were 30~60 min, 400~600 W and 50~70℃.In summary, the present study provided data support and basis for microwave extraction in the utilization of biomass resources.