Abstract: Based on the anisotropy semianalytical thermal analysis, the temperature field and thermal distortion of rectangle Nd:GGG crystal in a double side dislocation pumping laser was investigated. A maximum temperature rise of 309.73℃ happened on the front pumping face and the Gaussian radius w became 9.00mm with two 300W laser diode arrays side-pumping Nd:GGG laser crystal. After analyzing the working characteristics of the laser crystal, a thermal model that matches actual situation of the laser crystal was established, and the analytical expressions of the temperature field and thermal distortion field of the rectangle Nd:GGG laser crystal were obtained. With double side dislocation pumping the rectangle Nd:GGG crystal for 10s, there happened maximum thermal distortion of 28.97m and a maximum optical path difference of 13.02m. After stopping pumping for 200s, the maximum temperature rise dropped to 1.01%. These results provide theoretical basis for the optimized design of LD double side pumped heat capacity lasers.