Objective To investigate the imbalance of serum miRNAs expression profile and the changes of related signal pathways induced by PM2.5 in rats. Methods 40 6-week-old male Wistar rats were randomly divided into control group and PM2.5 low/medium/high dose group, once every 3 days for 70 days. Lung tissues were collected for pathological examination, and miRNA RNA SEQ high-throughput sequencing was performed. 16 HBE cells were cultured and treated with PM2.5 for 24～48 hours. After 16 HBE cells were transfected with mir-296-5p inhibitor and its negative control for 12 hours, the changes of Notch signaling pathway were detected by Western blotting. Results 67 miRNAs were differentially expressed in the lung tissue of rats in the intervention group, including 48 up-regulated and 19 down regulated, and 4 were more than 5 times higher, namely mir-296-5p, mir-27a, mir-182 and mir-92a-1-p5. Among them, mir-296-5p was up-regulated 7.85 times, which was the miRNA with the largest expression difference. After PM2.5 intervention, the expression of Notch1 protein and Hes1 protein decreased, while the expression of Beclin1 protein and cleaved caspase 3 protein increased(P＜0.05); After transfection with mir-296-5p inhibitor, the relative expression of Notch1 protein, Hes1 protein and Beclin1 protein increased significantly(P＜0.05). Conclusion Exposed to PM2.5, the expression profile of miRNAs in rat lung tissue is disordered, and the imbalance of mir-296-5p expression is the most obvious, and the imbalance of mir-296-5p expression can affect the function of lung epithelial cells through Notch signal pathway.