This study aimed to establish a microwave-assisted method (MAE) for the efficient extraction of polysaccharides from dandelion roots. This study investigated the molecular structure and bioactivity of the polysaccharides from dandelion roots. Extraction conditions were optimized using response surface methodology (RSM). The microwave extraction conditions were set to an extraction time of 42 min, an extraction temperature of 80 °C, and a solid-liquid ratio (g/mL) of 1:33. Under the optimized conditions, the highest dandelion root polysaccharides (DRP) yield was achieved (24.85 ± 0.457 %). Water-pure DRP (DRPw) and NaCl-pure DRP (DRPs) were purified by activated carbon decolorization and DEAE fiber column chromatography. The molecular weights of DRPw and DRPs were 8653 Da and 5930 Da, respectively. The Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the existence of α- and β-pyranose in DRPw and DRPs. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that DRPw and DRPs were semi-crystalline substances with irregular shapes and rough surfaces. Bioactivity assays revealed the good antioxidant activities of DRPw and DRPs. The present study provides useful information about DRP as natural antioxidants for the benefit of food.