Objective To investigate the regulatory effects of naringin on microglia polarization and Aβ clearance and cognition in APPswe / PS1dE9 transgenic mice. Methods Three-month-old male APPswe / PS1dE9 transgenic mice were randomly assigned to two groups: the model group and the naringin treated group (100 mg / (kg·d)). Non-transgenic mice were selected as the negative Control group and the naringin alone group (100 mg / (kg·d)). The mice were matched in age and weight. Mice in the negative control group and model group were given a conventional standard diet, whereas those in the naringin treatment group and naringin alone group were given a conventional standard diet containing 100 mg / (kg·d) naringin for 16 weeks. The novel object recognition test was performed to assess cognitive function. The effects of naringin on liver and kidney function in mice were assessed by enzyme-linked immunosorbent assays. The expression of M1- type and M2-type microglial markers was examined by quantitative real-time PCR. Immunofluorescence staining was conducted to determine the content of Aβ and the phagocytic effect of activated microglia cells on Aβ. Results Compared with the control group, APPswe / PS1dE9 mice exhibited a significantly decreased discrimination index in the novel object recognition test ( P< 0. 05). The mRNA expression level of M1-type markers ( CD16, TNF-α, iNOS, MCP-1) was remarkably upregulated (P< 0. 05), whereas the mRNA expression of M2-type markers (CD206, TGF-β, Arg1, YM-1) was significantly downregulated in the brains of APPswe / PS1dE9 mice (P< 0. 05). Furthermore, the Aβ-positive region was significantly elevated in the cerebral cortex and hippocampus of APPswe / PS1dE9 mice (P< 0. 05). Compared with the model group, naringin administration markedly increased the discrimination index in APPswe / PS1dE9 mice (P< 0. 05), restored the normal expression of M1-type and M2-type markers in brain tissues (P< 0. 05), reduced the positive area of Aβ, and promoted the phagocytosis of Aβ by microglia (P< 0. 05). There was no significant difference in liver and kidney function parameters among the groups (P> 0. 05). Conclusions Naringin can promote microglial polarization from the M1-type towards the M2-type, enhance Aβ phagocytosis by activated microglia, and subsequently improve cognition in mice.