This paper presents the application of the MAIRCA method to solve the multi-objective optimization problem (MOOP) in the design of a two-stage helical gearbox. The primary goal is to simultaneously improve transmission efficiency and reduce the overall gearbox volume. Three key design variables are considered: the gear ratio of the first stage and the coefficients of wheel face width (CWFW) for both the first and second stages. To effectively handle the conflicting objectives, the MAIRCA method is employed as a Multi-Criteria Decision-Making (MCDM) tool, while the MEREC method is adopted to determine the criteria weights. The results of the study provide optimal values for the selected design parameters, offering practical guidance for designing more efficient and compact two-stage helical gearboxes.