Total phenolics and flavonols of aqueous extract from different parts of Cudrania tricuspidata (fruit, root, leaf, and stem) and neuronal cell protective effects against oxidative stress-induced cytotoxicity were investigated. The neuronal cell protective effects of aqueous extract from different parts of C. tricuspidata was examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction, lactate dehydrogenase (LDH) release, and neutral red uptake assay. The overall relative neuronal cell protective effects of C. tricuspidata root by 3 assays were much higher than those of leaf, stem, and fruit. The aqueous extract of C. tricuspidata root also showed higher total phenolics than those of different parts. Therefore, our study suggested that the aqueous extract of root has strong protective effect on oxidative stress-induced neurotoxicity which is correlated with its high level of phenolics, particularly kaempferol, quercetin, and myricetin.