A thorough of thermoplastic polymer in the wax-based binder is essential for ensuring the dimensions and mechanical properties of 316L stainless steel metal injection molding parts. The effects of three thermoplastic polymers, High density polyethylene, High density polyethylene /Polypropylene and Polypropylene, on the dimensions and mechanical properties of 316L stainless steel metal injection molding parts have been compared in this paper. The tensile bar is tested to examine the dimensions and mechanical properties of sintered parts against different thermoplastic polymers in the binder. Among the three thermoplastic polymers in the binder considered herein, High density polyethylene /Polypropylene performs better than the others in solvent debinding stage and in terms of the metal injection molding compact quality. High density polyethylene /Polypropylene has significantly better length, width and thickness by up to 46%, 40%, 20%, respectively. The density, hardness and tensile strength of the sintered parts are 7.28 g/cm₃, 72.3 HRB and 579MPa.