Pleurotus eryngii (PE) contains polysaccharides and vitamins, and has been reported to have antidepression properties. P. eryngii polysaccharides (PEP) are one of the main components. Modulation of β-amyloid-induced neurotoxicity has emerged as a possible therapeutic approach to ameliorate the onset and progression of Alzheimer's disease (AD). The present study aimed to evaluate the protective effect of PEP on β-amyloid-induced neurotoxicity in cultured rat pheochromocytoma (PC12) cells and aging rats. After 28 weeks' treatment, exposure of PC12 cells to P. eryngii polysaccharides significantly elevated cell viability, decreased the levels of intracellular calcium, and attenuated the β-amyloid-mediated cell apoptosis. In aging rats, P. eryngii polysaccharides could decrease the production of APP in the brain by an action that is associated with a lowering of the iNOS, and COX-2 level. Our findings indicated that P. eryngii polysaccharides had potential neuroprotective actions against β-amyloid-induced neurotoxicity, which might be through modulating calcium channels, or downstream molecules involved in inflammation.