Abstract: The mechanism of the thermal stress damage and the distribution of plasma were studied in term of anti-reflection fused silica irradiated by 1064 nm laser. Based on the theories of thermal conduction and gas dynamics, theoretical model of thermal stress damage and combustion damage of anti-reflection fused silica induced by millisecond laser was analyzed. Thermal damage, stress damage and laser supported combustion wave of internal space of anti-reflection fused silica was simulated by COMSOL software. The simulation results show that, roughly with in the area of laser beam spot, the temperature increased obviously with large temperature gradient. Thermal expansion of this lasing area was restricted by the other part, causing internal stress of the material, in which radial stress and circumferential stress of upside surface reached their maximum values in the edge of laser spot. Stress damage was generated in irradiation center point or the edge of laser spot, with steady propagation of plasma. Speed of combustion wave gradually decreased with time from its maximum at the initial moment.