Mirror surface of high power laser would be deformed by the pressure of the coolant in a liquid cooling mirror system. In
order to eliminate the impact of pressure and vibration of cooling water to the stability of the output beam, a cooling
mirror with heatpipe is designed. With the same structure and conditions, solid mirror, water cooling mirror and heat
pipe cooling mirror are simulated by ANSYS program. The time-varying thermal deformations of the group mirrors after
60s under the net heat absorption of 12W/cm<sup>2</sup> are obtained. The maximal peak and valley difference value of mirror
surface deformation of solid mirror along Z-axis, water cooling mirror and heat pipe cooling mirror after 60s is 1.33μm,
0.845 μm and 0.1094 μm respectively.