The present work is about the determination of the most appropriate welding sequence for welding a gearbox housing. For this purpose, different welding sequences were evaluated by means of Finite Element numerical simulation. The simulation was based on a semi-coupled thermo-structural problem modeling, in which the structural solution depends on the thermal solution. The Goldak’s double ellipsoid model was used in the thermal analysis to simulate the heat source and its dimensions were determined from the expressions developed by Christensen. A thermo-elasto-plastic model was used in the structural analysis to simulate the material behavior, considering the von Mises yield criterion and the bilinear kinematic hardening rule. To simulate the material deposition, the birth and death technique was used. The thermo-dependent mechanical and physical properties of ASTM-A36 steel, the material used to construct the housing, were considered in this study. With the developed model four single pass welding sequences were evaluated, concluding that the most satisfactory results are obtained when methods for the control of the distortion are used.