Abstract: Carbon-based films are widely used in fuel cell bipolar plates due to their excellent corrosion resistance and chemical stability. In this paper, amorphous carbon (a-C) films were deposited on SS316L stainless steel ultra-thin strips by magnetron sputtering technology to enhance the corrosion resistance of proton exchange membrane fuel cell (PEMFC) bipolar plates. A Taguchi orthogonal design combined with SEM and electrochemical analyses was employed to evaluate the effects of working pressure, sputtering power, substrate bias, and deposition time. The optimal process parameters were determined using the TOPSIS multi-criteria decision-making method as 1.5 Pa working pressure, 150 W sputtering power,-250 V bias voltage, and 60 min deposition time. Under these conditions, the corrosion current density decreased to 1.61×10^-6 A/cm², corresponding to a corrosion rate of 0.018 mm/a. The results confirm that optimized magnetron sputtering significantly improves the corrosion resistance of stainless steel ultra-thin bipolar plates.