Laser absorbers are necessary for high power laser facilities to achieve effective control of the stray lights. However, the boundaries of the absorber light receiving surfaces are easily to be damaged by the laser, which may cause the pollution of the clean environment inside the facility. To solve this problem, based on methods of finite element analysis, light field distribution in medium of high-power laser absorber with its boundary of light receiving surface under conditions of no-transition， plan transition and curved surface transition were simulated. Effects of absorption glass boundary on light field were analyzed. Transformation regularity of the intensity and position of light field peak inside the medium were obtained. The results indicate that the damage of the absorber may be caused by the curved surface transition of the boundary. This research provides a reference for research of laser damage and absorber designing.