In this paper, the design of coating system, choose of materials, technology of fabrication, as well as the experimental results for the damage threshold and thermal deformation of the cavity mirrors of DF laser are reported. The experimental results show that the thermal deformation of he cavity mirrors of DF laser is about 0.3λ (λ=632.8 nm) under the power density of 21 kW/cm 2, and the damage threshold of the cavity mirrors of DF laser is higher than 40 kW/cm2.