Objective To investigate the role of the HSP90/PGAM5/DRP1 pathway in mediating mitochondrial fission and its therapeutic potential against Alzheimer's disease (AD).Methods Mice were randomly divided into the control group (C57BL/6J mice), model group (APP/PS1 double transgenic mice), and HSP90 inhibition group (APP/PS1 double transgenic mice treated with the HSP90 inhibitor). Learning and memory were assessed via the Morris water maze test. Pathological changes in the hippocampus were observed using hematoxylin-eosin (HE) staining. Serum tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) levels were quantified by enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry was used to detect the positive expression of p-MLKL. Western blotting was performed to measure hippocampal Tau protein phosphorylation and expression levels of proteins associated with the HSP90/PGAM5/DRP1 pathway.Results In the Morris water maze test, mice in the model group exhibited significantly longer escape latency and fewer platform crossings compared with the control group (P < 0.05). In contrast, mice in the HSP90 inhibition group showed significantly shorter escape latency and more platform crossings than those in the model group (P < 0.05). Pathological changes were observed in the hippocampal tissues of the model group. Immunohistochemistry revealed that the expression level of p-MLKL in the hippocampus was significantly higher in the model group than in the control group (P < 0.05), while the HSP90 inhibition group exhibited lower p-MLKL expression compared to the model group (P < 0.05). Compared with the control group, mice in the model group showed significantly decreased IL-4 levels and increased TNF-α levels in hippocampal tissues (P < 0.05). Compared with the model group, the HSP90 inhibition group exhibited increased IL-4 levels and decreased TNF-α levels (P < 0.05). Compared with the control group, the expression levels of HSP90, PGAM5, p-MLKL/MLKL, p-Drp1/Drp1, and p-Tau were significantly elevated in the hippocampus of the model group (P <0.05), while the levels of MFN1, MFN2, and ATP5a were significantly decreased (P < 0.05). Compared with the model group, the HSP90 inhibition group showed significantly reduced expression of HSP90, PGAM5, p-MLKL/MLKL, p-Drp1/Drp1, and p-Tau (P <0.05), along with increased expression of MFN1, MFN2, and ATP5a (P < 0.05).Conclusion The HSP90/PGAM5/DRP1 pathway contributes to AD progression by regulating mitochondrial fission. Inhibition of this pathway significantly alleviates mitochondrial dysfunction, suppresses neuroinflammation, and improves cognitive function, providing a novel therapeutic target for AD treatment.