Aging is a major risk factor for Alzheimer's disease (AD). With the prevalence of AD increased, a mechanistic linkage between aging and the pathogenesis of AD needs to be further addressed. Here, we report that a small ubiquitin-related modifier (SUMO) modification of p53 is implicated in the process which remarkably increased in AD patient's brain. Mechanistically, SUMOylation of p53 at K386 residue causes the dissociation of SET/p53 complex, thus releasing SET into the cytoplasm, SET further interacts with cytoplasmic PP2A and inhibits its activity, resulting in tau hyperphosphorylation in neurons. In addition, SUMOylation of p53 promotes the p53 Ser15 phosphorylation that mediates neuronal senescence. Notably, p53 SUMOylation contributes to synaptic damage and cognitive defects in AD model mice. We also demonstrate that the SUMOylation inhibiter, Ginkgolic acid, recovering several senescent phenotypes drove by p53 SUMOylation in primary neurons. These findings suggest a previously undiscovered etiopathogenic relationship between aging and AD that is linked to p53 SUMOylation and the potential of SUMOylated p53-based therapeutics for neurodegeneration such as Alzheimer's disease.