In the process of laser heat fusion sealing of a single glass tube, the quality of processing is inextricably linked to the temperature distribution inside the tube. Under the consideration of surface heat radiation, internal heat conduction of material and air heat convection, the finite element simulation software, which called COMSOL Multiphysics was adopted to carry out simulation of the temperature field of high borosilicate glass tube under the action of CO₂ laser, the change rule of the temperature field distribution with time was analyzed, and the effects of laser power, laser spot radius and rotation speed on the temperature distribution of the glass tube were compared. Simulation results show that the higher the laser power, the smaller the spot radius, the lower the rotational speed of the glass tube, and the higher the temperature of the glass tube. According to the simulation results, the process requirements of laser processing of high borosilicate glass tube can be achieved by selecting suitable processing parameters. This study provides an important theoretical basis for the selection of process parameters of subsequent glass tube laser hot fusion sealing.