In order to solve conflicting decision problems, multi-criteria decision making (MCDM) methods are used to make the best choice among many criteria. In this research, sixteen different samples of melt compounded polyamide 6 (PA6) and multi-walled carbon nanotubes (MWCNTs) were studied. The raw materials were compounded using a twin-screw extruder and the samples were chosen based on an L-16 orthogonal array of Taguchi approach. The alternatives of the problem were samples produced under different injection parameters including holding pressure, injection temperature, and with various weight percentages of MWCNTs. The chosen criteria were tensile strength, elastic modulus, Charpy impact strength, Rockwell hardness, and cost. Analytical hierarchy process (AHP) was used to weight the criteria and due to the results, tensile properties were the most important criteria with the weight of 0.319. In the next step, a technique for order preference by similarity to an ideal solution (TOPSIS) and the multi-objective optimization on the basis of ratio analysis (MOORA) were implemented to rank the alternatives. Based on the considered criteria the samples containing 1 wt% of MWCNTs was selected as the best alternatives.