Purpose To evaluate the efficacy and safety of CO2-Laser Assisted Sclerectomy Surgery (CLASS) with 5-fluorouracil (5-FU) in treating open-angle glaucoma (OAG) in Chinese patients. Methods: This was a retrospective, uncontrolled, interventional case series. All patients from 2016 to 2017 who received CLASS were recruited in this study. The primary outcome was the change in intraocular pressure (IOP) and the number of IOP-lowering medications over a 12-month follow-up period. Adverse events were evaluated as secondary outcomes. Results: Data were collected from forty-two eyes of 31 patients. The average preoperative IOP was 31.33 ± 7.60mmHg. The mean percentage of IOP reduction from baseline at postoperative months (POM) 1, 3, 6, 9, and, 12 were 48.1% ± 24.6%, 51.4% ± 19.3%, 51.2% ± 17.2%, 50.9% ± 15.0%, 49.2% ± 16.3%, respectively (all P < 0.001). The number of glaucoma medications decreased from a baseline of 3.02 ± 0.81 to 0.05 ± 0.22, 0.10 ± 0.37, 0.12 ± 0.40, 0.17 ± 0.44, and 0.24 ± 0.58 at POM 1, 3, 6, 9, and 12, respectively (all P < 0.001). At POM 1, 3, 6, 9, and 12, complete success rates were 66.7%, 73.8%, 76.2%, 69.1%, and 71.4%, respectively. At POM 1, 3, 6, 9, and 12, qualified success rates were 71.4%, 82.0%, 85.3%, 83.3%, and 90.5%, respectively. Major postoperative complications include peripheral iris synechia, iris incarceration, and anterior chamber shallowing. Conclusions: CLASS with 5-FU shows safety and efficacy for decreasing IOP and the number of IOP-lowering medications over a 12-month follow-up period. It could be an alternative treatment for patients with OAG.