Objective To study the composition and structural characteristics of polysaccharides from roasted beans of Coffea arabica.Methods Roasted beans of C. arabica were used as raw materials. The hot water extraction combined with alcohol precipitation method was optimized using the response surface methodology to extract polysaccharides. The crude polysaccharide was purified using the Sevag method, macroporous resin, cellulose column, and gel separation technology. Total sugar, total phenol, total flavonoid, and monosaccharide compositions were analyzed using the phenol-sulfuric acid method, Folin-Ciocalteu assay, NaNO₂-AlCl₃-NaOH method, and ion chromatography, respectively. The structural characteristics of the polysaccharides were characterized by infrared spectroscopy (IR) and scanning electron microscopy (SEM). Additionally, the in vitro antioxidant activity of the polysaccharides was evaluated.Results The optimal extraction conditions for polysaccharides from roasted coffee beans were as follows: extraction temperature of 80.4 ℃, extraction time of 48 min, liquid-to-solid ratio of 15.3∶1 (mL/g), and ethanol volume fraction of 75%. Under these conditions, the polysaccharide yield was (7.56±0.26)%. After purification, five polysaccharides (RBP1, RBP2, RBP3, RBP4, and RBP5) were obtained, which were primarily composed of galactose (Gal), rhamnose (Rha), glucose (Glc), arabinose (Ara), and mannose (Man). The infrared spectra of the polysaccharides showed characteristic absorption peaks near 3 300~3 500 cm^-1, 2 900~3 000 cm^-1, 1 600 cm^-1, 1 400~1 300 cm^-1, and 1 000 cm^-1. SEM images showed that the polysaccharides exhibited a series of compact, porous structures, with RBP4 displaying a dense and regular pore structure. The antioxidant activity results showed that RBP0 had the strongest antioxidant capacity, which increased with concentration in the range of 0.1~0.5 mg/mL. The DPPH radical scavenging ability increased from (1.53±0.32)% to (82.85±0.61)%, and the iron reduction ability (FRAP method) increased from (0.39±0.000 48) mmol/g Fe²⁺ to (3.03±0.001 9) mmol/g Fe²⁺.Conclusion The polysaccharides from roasted beans of C. arabica are vesicular polysaccharides primarily composed of galactose, rhamnose, glucose, arabinose, and mannose.