Objective To explore the operability of concomitant ablation for the patients with valvular heart diseases with left atrium bigger than 60 mm. Methods We prospectively included 306 patients with concomitant ablation in our hospital between 2013 and 2015 year. Based on diameter of left atrium measured by intra-operative transesophageal echocardiography (TEE), we separated these patients into two groups including a group L (left atrium >60 mm, 93 patients, 55 males and 38 females at age of 57.0±10.1 years) and a group S (left atrium <60 mm, 213 patients, 120 males and 93 females at age of 55.2±9.9 years) and followed them on 4 time points (time on discharge, three months, six months, and one year after surgery). Then, we analyzed the impact of left atrial size on cardioversion outcome of surgical ablation based on the following data. Results The successful rate of the group S and the group L in the 4 time points was 72.8% vs. 75.3%, 74.2% vs. 75.3%, 78.9% vs. 77.4%, and 77.0% vs. 77.4%, respectively . The result of both univariate logistic regression analysis and receiver operation characteristic(ROC) curve analysis showed that there was no statistical difference in cardioversion rates between the group S and the group L. And there was no evident correlation between size of left atrium and ablation failure. Conclusion Patients with left atrium enlarged from 60 mm to 70 mm can achieve the same satisfactory results in cardioversion, and should not be the contraindication of concomitant surgical ablation.