Abstract: Laser heat-conduction welding (LHCW) is a laser welding mode within a certain range of laser power density.In this paper,the ranges of laser power applied to LHCW are solved based on the 3D analytical model of welding temperature field for LHCW and the model had been rectified.The relationships between the critical power of LHCW and welding velocity,the position of laser focus are studied.At last,the critical power of LHCW is rectified by experiments,and the rectified results show that the range of critical power for LHCW solved from the model of welding temperature field is consistent with that of experiments,and indicate that this method to solve the range of critical power is feasible and reliable.