In this article, a grey–fuzzy-based algorithm with the Taguchi method is proposed to find the optimal process parameters’ setting for submerged arc welding process of AISI 1518 grade steel on the multiple performance characteristics such as tensile stress, toughness and hardness of weldment. Various process parameters, such as wire feed rate, stick out and traverse speed of welding process, were exposed by investigation. The proposed algorithm, coupling the grey relational analysis with the fuzzy logic, obtains a grey–fuzzy reasoning grade to evaluate the multiple performance characteristics according to the grey relational coefficient of each performance characteristic. Through the grey–fuzzy logic analysis, the optimization of multiple performance characteristics can be converted into the optimization of a single grey–fuzzy reasoning grade. Finally, the process parameters are optimized by the Taguchi method. The optimal process parameter combination becomes W_f-3 S_o-1 T_s-3, that is, the wire feed rate at level 3 (2 m/min), stick out at level 1 (20 mm) and traverse speed at level 3 (0.9 m/min) for maximum tensile stress and toughness and minimum hardness of weldments. It is also observed stick out on the overall mechanical property is more significant compared with other welding parameters (wire feed rate, traverse speed).