A multiple inclusion model of transparent optical components irradiated by millisecond long pulse laser was established. The temperature and stress field distribution and process of a K9 based component coated with SiO2/Al2O3 anti-reflection films irradiated by millisecond laser were numerical calculated and analyzed. The results show that multiple micro-inclusions can serve as heating source which induce devastating damages under the action of a millisecond laser. The damage happens both from front and back surfaces. The front surface damage is caused by heat and stress while the back surface damage is dominant by stress. The damage morphologies indicated by numerical results meet well with the experimental morphologies observed.