Objective To evaluate the value of preoperative B-type natriuretic peptide （BNP） level in predicting new onset atrial fibrillation （AF） in patients after coronary artery bypass grafting （CABG）. Methods We electronically searched PubMed，EMbase，Cochrane library，CNKI and VIP databases from the establishment of those databases to November 2012. Evaluation standard of diagnostic tests was used to identify and screen literatures which investigated correlations between preoperative BNP levels and new onset AF of patients after CABG. Quality Assessment of Diagnostic Accuracy Studies （QUADAS） was used to evaluate study quality of included literatures. RevMan 5.0 was used for heterogeneity test. Meta-Disc 1.4 software was used for meta-analysis. Included studies were weighted and then combined. Sensitivity，specificity，diag- nostic odds ratio （DOR），positive likelihood ratio，negative likelihood ratio and corresponding 95% confidence interval（95% CI）were calculated. Summary receiver operating characteristic （SROC） curve was drawn，and the area under the SROC curve （AUC） was analyzed. Results A total of 236 studies were identi?ed，and 5 studies met the eligibility criteria including 802 patients for analysis. There were 228 patients with postoperative new onset AF，and 574 patients without postoperative AF. The quality of the included literature was relatively high. DOR of preoperative elevated BNP level with postoperative new onset AF was 4.15 with 95% CI 2.90 to 5.95. Pooled sensitivity was 0.78 with 95% CI 0.72 to 0.83，pooled specificity was 0.58 with 95% CI 0.54 to 0.58，pooled positive likelihood ratio was 1.91 with 95% CI 1.42 to 1.56，pooled negative likelihood ratio was 0.42 with 95% CI 0.32 to 0.54，and the AUC of SROC was 0.79 （Q=0.72）. Conclusion Preoperative elevated BNP level is significantly correlated with new onset AF after CABG，is a powerful predictor of postoperative AF，and can be used to predict new onset AF after CABG to a certain extent of reliability.