Oral infection with Porphyromonas gingivalis (P. gingivalis), a kind of pathogenic bacteria causing periodontitis, can increase the risk of Alzheimer's disease (AD) and cause cognitive decline. Therefore, precise intracerebral antimicrobial therapy to reduce the load of P. gingivalis in brain may serve as a potential therapeutic approach to improve AD-like cognitive impairment. A kind of nano-delivery system precisely targets bacteria in the brain through coating P. gingivalis stimulated macrophage membrane onto the surface of platinum nanoclusters (Pg-M-PtNCs). Approximate 50 nm spherical Pg-M-PtNCs demonstrate good biocompatibility and the pretreated macrophage membranes can inhibit macrophages phagocytosis and increase the adherence to bacteria. Pg-M-PtNCs can significantly inhibit the growth of P.gingivalis in vitro, and are effectively delivered and remain at the infection site in the mice brain to reduce the bacterial load and neuronal damage, and then improve the AD-like cognitive dysfunction in the chronic periodontitis mice. Platinum nanoclusters coated with P. gingivalis pretreated macrophage membrane play an important role in targeting bacteria in the brain, and effectively improve AD-like cognitive function disorder caused by P. gingivalis infection in the brain.