Abstract: In this paper, the distributions of temperature and thermal stress in the transparent optical materials, resulting from the laser energy-absorption of a defect, were obtained analytically. When the shape of the defect is point-like, the maximum value of normal stress in y-direction locates on the boundary. With the increase of x coordinate, the stress decreases obviously. But when the shape of flaw is changed to linear, the normal stress in y-direction is minimum at the boundary and is singular at two ends of the linear flaw. Based on a simple crack model, the relative stress intensity factor (SIF) and effects of various parameters on SIF were analyzed and discussed. The main conclusions include that SIF increase monotonously with the enlargement of the ratio between the crack length and t