In the study conducted, pure Low Density Polyethylene (LDPE) and cotton fibre reinforced composites were produced via a custom-made single screw extruder. The aim is to understand and determine the optimum parameters such as screw speed and processing temperatures on the mechanical properties of the composites with different cotton fiber (12.5 %wt and 25 %wt) content. For this purpose two screw speed levels (15 and 30 rpm) and two temperature set levels (145, 150, 155, 160 and 165, 170, 175, 180) for zone 1, zone 2, zone 3 and die were chosen. The effects of the parameters on mechanical properties were studied using tensile, three-point bending and impact test. According to pioneering results, it is worthnoting that tensile properties are highly dependent on the extrusion parameters with respect to cotton fiber content.