Abstract: Using Platycodon grandiflorum as the raw material and polysaccharide yield as the evaluation index, this study investigated the effects of deep eutectic solvent types, molar ratio, liquid-to-material ratio, water content, and extraction time on polysaccharide extraction. Single-factor experiments and response surface methodology were employed to optimize the extraction process. The structure of the extracted polysaccharides was characterized using ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The antioxidant activity of Platycodon grandiflorum polysaccharides was evaluated by assessing their scavenging abilities against ·OH, ABTS⁺·, and DPPH·. After optimization, the best extraction process for Platycodon grandiflorum polysaccharide was determined as follows: Extraction temperature 79 ℃, liquid-to-material ratio 20.5:1, molar ratio 2.2:1, extraction time 1.5 h, and water content 30%. Under these conditions, the yield of Platycodon grandiflorum polysaccharides was measured to be 31.17%, which was approximately 3.11 times higher than that obtained using the water extraction method. UV-Vis spectra revealed no characteristic absorption peaks of nucleic acids or proteins near 260 nm and 280 nm. FT-IR spectroscopy identified typical characteristic absorption peaks of polysaccharides at multiple wavenumbers, including 3363, 2931, 1739, 1639, 1422, and 1025 cm⁻¹. SEM showed that the surface of Platycodon grandiflorum polysaccharides exhibited a sheet-like structure with a relatively rough texture, few pores, and distinct wrinkles. The antioxidant activity study demonstrated that the maximum scavenging rates of Platycodon grandiflorum polysaccharides on ·OH, ABTS⁺·, and DPPH· were 95.85%, 66.96%, and 52.45%, respectively. In conclusion, the choline chloride/urea DES system could significantly improve the extraction yield of Platycodon grandiflorum polysaccharides, which showed strong antioxidant activity.