A compensation system of mirror deformation is developed,and it is composed of an annular TEC,temperature force components and a control circuit.Under the effect of annular temperature,the mirror produces inner concave or external convex spherical deformation,which can compensate the defocusing amount brought by the thermal deformation of the mirror itself or transmission optical element in laser system.The experiments of temperature-deformation and laser irradiation-temperature-deformation are conducted by using a flat mirror with the diameter of 50mm and the thickness of 10mm,and a interferometer is used to monitor the surface deformation.The temperature-deformation curve is obtained;it shows the central displacement of mirror varies with the temperature linearly.The coefficient of temperature-central displacement is 0.088μm/℃,and the central displacement is over 2.5μm under 50 ℃。When 162W laser is input in the mirror,self-compensation of thermal distortions of the mirror reduces from 0.3μm to 0.08μm;the thermal deformation of transmission optical element reduces from 0.28μm to 0.066μm.