This study focuses on improving the quality of lavabo basin products at Thien Thanh Bathware Company Limited. by applying quality analysis tools such as process flowcharts, check sheets, Pareto charts, and cause-and-effect diagrams. The analysis identified two major defects affecting product quality: impurities and firing cracks. Based on root cause analysis, the study proposes three groups of solutions: (1) cross-training and standardized operation models to enhance workers’ skills; (2) periodic maintenance plans for the vibrating screen to ensure stable equipment performance; and (3) regular mold maintenance to detect early wear or damage. These solutions aim to improve product quality, reduce defect rates, and increase production efficiency.