Abstract: As an effective computational method, the numerical simulation of welding processes has been widely used in evaluating welding temperature fields and residual stress distributions. In the numerical simulation process, the selection of the welding heatsource model and the confirmation of model parameters will directly affect the accuracy of the calculation and the evaluation results. Some heat-source models commonly used in numerical simulations of the arc welding process were surveyed in this article; advances in their development were introduced, and their characteristics and applicability were analyzed. As basic heat-source models, the Gauss surface heat-source modes and double-ellipsoid-volume heat-source model have been widely used in the numerical simulation of arc welding for workpieces with a relatively small size and a regular welding trajectory, and the calculation results have been demonstrated to be accurate. In the numerical simulation of arc welding processes for large and thick workpieces welded using multi-layer or multipass techniques and for workpieces with a complex welding trajectory, the simplified heat-source model and temperature-substitution heat-source model are chiefly applied, and the calculation efficiency and precision can be well balanced. The heat source of multi-wire arc welding is comparatively complicated, and the superposed model of modified double-ellipsoid-volume heat-source models can ensure a certain accuracy of the calculation results. The combined heat-source model is more flexible in the shape description of the molten pool and has advantages in the numerical simulation of arc welding with deep penetration. The all-around induction and analyses in this article are expected to provide valuable reference and guidance for the selection of a heat-source model and for confirming model parameters in the numerical simulation of arc welding processes.