The wide industrial cultivation of Pleurotus eryngii (P. eryngii) has resulted in the massive production of mushroom residues (MR) with low-efficiency utilization. In the present study, the P. eryngii enzymatic residue polysaccharide (PERP) was obtained from the P. eryngii residues. The characterization analysis showed that PERP was polysaccharides comprised of five kinds of monosaccharides with molecular weight of 2.05 × 103 Da. PERP also showed rough surface and appeared as spherical structure dispersed in aqueous solution. The animal experiment analysis demonstrated that PERP exhibited potential anti-ageing effects on the brain, liver, kidney and skin, possibly by scavenging reactive radicals, improving the antioxidant status, supressing lipid peroxidation, enhancing organ functions and ameliorating histopathological damage. These results may provide a reference for the efficient utilization of P. eryngii residues in exploring MR-derived functional foods or drugs that delay the ageing process.