Objective：This study aims to analyze the correlation between plasma exosomal miR-409-3p and perioperative neurocognitive disorders （PND） after coronary artery bypass grafting. Methods：A total of 76 patients undergoing coronary artery bypass graft surgery were enrolled in this study. Neuropsychological test assessments were performed 1 day before and 7 days after surgery，and the patients were divided into PND group（n=24） and non-PND group（n=52） according to the evaluation results. The plasma exosomes of all patients were extracted，and were identified by transmission electron microscopy，particle size analysis，and Western blot. The qRT-PCR was used to detect the expression level of exosomal miR-409-3p. Logistic regression analysis was used to evaluate the risk factors for PND. Results：There were statistical differences between the two groups in age，operation time and education years. The expression of plasma exosomal miR-409-3p in PND patients was higher than that in non-PND patients. Age，operation time，and plasma exosomal miR-409-3p were independent risk factors for PND. Conclusion：The highly expressed plasma exosomal miR-409-3p can be used as a new molecular marker for PND in patients undergoing coronary artery bypass graft surgery.