Background. Unroofed coronary sinus syndrome (UCSS) is rare and often associated with Left superior vena cava (LSVC). We report our experience in 159 patients with UCSS during a 20-year period in terms of clinical features, diagnosis, associated anomalies, surgical procedures and late outcomes. Methods. Between May 1998 and May 2019, 159 patients with UCSS were treated surgically and followed up. UCSS was confirmed by preoperative echocardiography or CT scan in 97 patients and by the surgeons during surgery in 62. LSVC directly drained into the left atrium (LA) was found in 100 cases. In these patients, 8 cases of LSVC were ligated, 59 cases were reconstructed the intracardiac tunnel to drain LSVC to right atrium (RA), and the extracardiac procedure was constructed to lead the LSVC draining to RA in 2. The associated cardiac lesions were corrected concomitantly. Results There were 5 hospital deaths. We followed up 143 early survivors, and there was no death. Except for one case of avulsion of the patch in which LSVC was drained by internal tunnel, there were no serious complications in other follow-up patients. Conclusion. UCSS is often misdiagnosed in the preoperative evaluation of congenital heart diseases. Preoperative transthoracic echocardiography (TTE) is still the most important method in the diagnosis of UCSS. When associated with LSVC, UCSS should be considered as a possible additional finding．We performed different surgical approaches to deal with the different types of UCSS with LSVC with a good result.