In this study, we conducted temperature, pressure, and stress deformation calculations for the tubing of a specific heavy oil thermal recovery well. Subsequently, we used the axial force on the tubing at the depth of the thermal fluid generator as a boundary condition and incorporated it into numerical simulation software to analyze the thermo-fluid-solid coupled mechanical characteristics of the generator under these operating conditions. Our findings indicate that the cooling water within the generator effectively isolates radial heat transfer from the thermal fluid. Moreover, under steam injection conditions, the maximum von-Mises stress in the generator is concentrated at the head-shell weld.