In order to solve thermal effect of laser crystal induced by high power diode laser endpumped,the thermal deformation on pump face of laser crystal was exactly calculated. Through work characteristic analysis of laser crystal in diode laser end-pumped all-solid-state lasers,a thermal model of rectangle laser crystal was built. Based on the heat conductive equation,a new solution of Poisson equation was introduced and the general analytical expression of thermal deformation of rectangle laser crystal was obtained. And thermal deformation influenced by diode laser eccentric-end-pumped was investigated. Compared to the finite-element analysis or other numerical solutions,the analytical solution will not produce any calculation error. The analytical solution of thermal deformation will supply a theoretical instruct for solving thermal effect of laser crystal and improving the performance of lasers.