为了改善激光晶体热效应，建立了矩形截面激光晶体热模型，通过求解热传导泊松方程，比较了矩形截面Nd∶YVO4和Nd∶GdVO4及Nd∶GdYVO4晶体的温度场分布和抽运端面的热形变，计算了由抽运端面热形变引起的光程差和总的光程差。由比较结果可知，在相同情况下，Nd∶YVO4,Nd∶GdYVO4及Nd∶GdVO4晶体的端面中心最高温升分别约为320℃,342℃和190℃，总光程差最大为1.7μm，2.11μm和1.3μm。结果表明，Nd∶GdYVO4晶体端面中心最高温升及总光程差均为最小，更适用于大功率LD端面抽运；对于大功率全固态激光器，由端面热形变引起的光程差对晶体热焦距有较大影响。

To improve the thermal effect of laser crystal，the rectangle thermal conduct model of laser crystal was established. The temperature distribution and end-thermal deformation of rectangle Nd∶YVO4/Nd∶GdVO4/Nd∶GdYVO4 laser crystals were obtained after solving Possion equation, and the optical path difference (OPD) induced by end-thermal deformation and the total OPD were calculated. After comparison, it was shown that in the same condation, the highest central temperatures of the pumped face of Nd∶YVO4, Nd∶GdYVO4 and Nd∶GdVO4 crystals were 320℃, 342℃and 190℃, the biggest total OPD were 1.7μm, 2.11μm and 1.3μm respectively. The results show that the central temperature rise and the total OPD of Nd∶GdYVO4 crystal are the smallest and it is fitter for the pumped face of LD with high power. The study shows that the OPD induced by end-thermal deformation have a large influence on thermal focal length of laser crystals for solid-state lasers with high power.