Abstract: Based on the characteristics of non-revolving symmetry of the welding pool and the taper-shaped weld beam for the electronic beam welding and other high energy welding, a model of transformable double-ellipse gauss attenuation body heat source with an inflexion point is built to simulate the shape of the weld better, and the transformability of the new source model makes it useful in both high energy welding and usual one. In the building process of the model, a clear function formula is put forward for the frontal and rear energy distribution, besides, the finite element analysis software Marc is used to analyse the simulating results between the new source model and other one, and the new model is approved to be reasonable as well as extensible.