Objective To investigate the effect of applying intraoperative epicardial echocardiography (IEE) on preoperative monitoring and evaluating the clinical result of cardiac surgery. Methods We retrospectively analyzed the clinical data of 248 patients treated in the Affiliated 105 Hospital of People’s Liberation Army and the First Affiliated Hospital of Anhui Medical University from June 2008 to May 2015. There were 108 males and 140 females. The age ranged from 7 months to 71 years. There were 113 patients diagnosed with the congenital heart disease (CHD) at the mean age of 11.89±14.74 years. There were 135 patients diagnosed with valvular heart disease at the mean age of 47.20±14.57 years. All patients underwent IEE during operation. Results In 113 patients with CHD, we found new deformities and corrected preoperative diagnosis before cardiopulmonary bypass (CPB) and we identified surgical complications after CPB by IEE. Other deformities and left atrial thrombus were found in 135 patients with valvular heart disease by IEE before CPB. After CPB, paravalvular leak and mitral regurgitation were found, therefore we took action immediately. Conclusions IEE can improve the preoperative diagnosis and reduce perioperative complications, which has value of application during cardiac surgery.