Considering the non- uniform absorption of mid-infrared film with high reflectivity, the model for the deformable mirror (DM) with high reflectivity films is built up using the finite element analysis software ANSYS. The temperature rise and thermal distortion of the DM radiated by the continuous laser beam are calculated, and their effects on beam quality are analyzed quantitatively. The results indicate that the nonuniform absorption of the high reflectivity film should not be neglected by using finite element analysis software. The narrower the heads spacing are, the higher the spatial frequency caused by the thermal distortions is. The effect is most obvious for the case of the incident laser beam with the peak-to-valley (PV) value of the wave distortion similar to that of the thermal distortion. For the given total absorption energy, the higher the incident laser power is, the more obvious the effect on beam quality caused by the thermal distortion is. In addition, according to different heat transfer conditions, the effect of the thermal distortion of the DM on beam quality is also discussed, and the local heat transfer mode is proposed according to the mechanism of the thermal distortion.