Background and aimsPostoperative atrial fibrillation (POAF) is a frequent complication following cardiac surgery and is associated with adverse clinical outcomes. Our study aimed at determining the clinical and echocardiographic predictors of POAF in patients with cardiac surgery and management of this group of patients may improve their outcome. MethodsWe prospectively enrolled patients from the department of cardiovascular surgery in the Second Hospital of Tianjin Medical University from October 23, 2020 to October 30, 2022, without a history of atrial fibrillation. Cox regression was used to identify significant predictors of POAF. ResultsA total of 217 patients (79 [36.41 %] were female, 63.96 ± 12.32 years) were included. 88 (40.55 %) patients met the criteria for POAF. Cox regression showed that preoperative left atrial diameter (LAD) (HR: 1.040, 95 % CI 1.008–1.073, p = 0.013) and postoperative QRS/LVEDD (HR: 0.398, 95 % CI 0.193–0.824, p = 0.013) and E/e’ (HR: 1.029, 95 % CI 1.002–1.057,p = 0.033) were predictors of POAF. ConclusionPreoperative LAD and postoperative QRS/LVEDD and E/e’ were predictors of POAF in patients undergoing cardiac surgery. Trial registration sitehttp://www.chictr.org.cn Registration numberChiCTR2200063344.