tau hyperphosphorylation, mitochondrial dysfunction and oxidative stress, and neuroinflammatory response. [3] Among them, the amyloid theory that focuses on excessive deposition of β-amyloid (Aβ) has been extensively studied with wide acceptance. [4] In this theory, imbalance of Aβ metabolism and catabolism in the central nervous system (CNS) has been regarded as the main reason for AD-like pathology. [5] Aβ is the product of a proteolytic process of a transmembrane protein, amyloid precursor protein (APP), by β-secretase 1 (BACE1, β-site APP cleavage enzyme 1) and the γ-secretase. [6] The overgeneration and abnormal aggregation of Aβ 1-42 can cause the collapse of dendritic spines and neuronal loss, induce oxidative stress, and promote inflammatory by activating microglia, which in turn exacerbates the pathogenesis of AD. [7] Several strategies focus on blocking Aβ aggregation and alleviating Aβ-mediated neurotoxicity have been developed, including aggregation inhibition, copper chelation, Aβ photo-oxidation, fibril thermal dissociation, and Aβ degradation. [8] However, many Aβ targeting pharmacological treatments failed to slow down genitive decline or improve global functioning in phase 3 clinical trials although with definite efficacy at animal model. [9] Besides the pathological discrepancy between real clinical patient and AD animal model, [10] another important reason is that AD is a multifactorial disease and therapy targeting Aβ alone is far more enough. [11] Despite significant Alzheimer disease (AD) is the leading cause of dementia that affects millions of old people. Despite significant advances in the understanding of AD pathobiology, no disease modifying treatment is available. MicroRNA-124 (miR-124) is the most abundant miRNA in the normal brain with great potency to ameliorate AD-like pathology, while it is deficient in AD brain. Herein, the authors develop a DNA nanoflowers (DFs)-based delivery system to realize exogenous supplementation of miR-124 for AD therapy. The DFs with well-controlled size and morphology are prepared, and a miR-124 chimera is attached via hybridization. The DFs are further modified with RVG29 peptide to simultaneously realize brain-blood barrier (BBB) penetration and neuron targeting. Meanwhile, Rutin, a small molecular ancillary drug, is co-loaded into the DFs structure via its intercalation into the double stranded DNA region. Interestingly, Rutin could synergize miR-124 to suppress the expression of both BACE1 and APP, thus achieving a robust inhibition of amyloid β generation. The nanosystem could pro-long miR-124 circulation in vivo, promote its BBB penetration and neuron targeting, resulting in a significant increase of miR-124 in the hippocampus of APP/PS1 mice and robust therapeutic efficacy in vivo. Such a bio-derived therapeutic system shows promise as a biocompatible nanomedicine for AD therapy.