Abstract: Based on the thermal conduction equations and thermalelastic equations, while the laser speckle radius on the reflectors are much larger than or almost approximate to the thermal diffusion lengths of the substrate materials, and while the reflectors boundaries are constrained or unconstrained, the maximum temperature rise, thermal distortion and thermal stress of silicon or silicabased multilayered infrared CW laser reflectors are calculated by a finite element analysis method. And the dependences of these parameters on the laser speckle radius is discussed. The results indicate that the ultimate axial displacements on the surfaces of the reflectors are approximately linear with the incidence beams radius while the reflectors have unconstrained boundarties, but the ultimate thermal