Abstract: As an efficient and reliable technical means, numerical simulation can effectively and comprehensively analyze the distribution of temperature field in the welding process. In the numerical simulation, the heat source model is used to replace the welding heat input, and the accurate heat source model is the basis to obtain the accurate temperature field.In this paper, the existing heat source models are sorted out, classified and summarized, and the characteristics, limitations and applicable welding scenarios of different heat source models are analyzed and summarized. Gauss heat source is suitable for welding methods with low welding speed, low arc impact force and small thickness of welding plate; Double ellipsoidal heat source is suitable for welding methods with high welding speed, large arc impact force and large thickness of welding plate; In the numerical simulation of large-scale components, the calculation efficiency can be greatly improved by using the strip segmented moving heat source; When the shape of weld pool is complex and the welding heat input needs to be divided into two parts, the simulation results obtained by using the combined heat source are more accurate than the single heat source; For the welding process with obvious dynamic characteristics, the dynamic heat source model has more advantages than the static heat source model.