Natural fiber reinforced composites are recognized as better materials for structural components due to their inherent properties. However, milling these materials presents a number of problems, such as surface delamination, which appeared during the machining process, associated with the characteristics of the material and the cutting parameters. Therefore, in this study, machining parameters and the influence of the banana fibers under delamination were investigated. Result showed that machining parameters has a significance effect on the delamination of banana fiber reinforced polyester composites.