This study was conducted to evaluate the influence of four-thread overlock seam width on seam durability on knitted fabrics. The research results will be used to improve the quality of teaching sewing techniques for students at An Giang Vocational College. Through the process of experimentation and data analysis, the research has drawn important conclusions about the optimal seam width, thereby helping to improve the quality of garment products. Research conducted on T-Shirt and Polo Shirt sportswear samples from knitted fabric with Interlock weave with 95% Polyester, 5% Spandex composition made on a 4-thread overlock machine (overlock seam). 514 ) with Epic suture and Gramax suture.