Through using a new laser bending process, the distribution of expected pre-stress was obtained on the heated zone of AISI 304 steel foil with thickness of 0.1 mm by applying initial displacement to the sample’s free end. Considering the characteristics of laser bending, three-dimensional (3D) thermomechanical finite element method (FEM) models of laser bending process with various pre-stresses were developed based on the buckling mechanism (BM). Through comparing the simulation results of different models, the mechanism of laser bending with pre-stresses was explained. The simulation results show that the deformation of the stainless steel foil under buckling mechanism depends on the integration of the thermal stress and the pre-stress when the laser beam irradiates the foil. The forming performance can be improved significantly under pre-stress, and the deformation direction can also be controlled easily by changing the direction and value of the pre-loading. The bending angles of the steel foils increase remarkably with the increase of the pre-loading, and both are almost in linear relationship.