A physical model of columned optical material irradiated by repetitive pulses laser was established. The distributions of temperature and stress profile were studied by the use of a 2-D model of heat conduction. By using a example of K9 glass in numerical calculation,it is shown that damage threshold of laser intensity in facus center was influenced by the number,width,repetitive frequency and laser radius of pulse laser. Under most condition,the damage of K9 glass is stress damage.