In order to solve the thermal effect problem of diode bar side-pumped laser slab,a temperature modeling of laser slab according to the practical situation was established based on analysing on the temperature field and thermal distortion field of diode bar side-pumped laser slab and discussing on its working characteristics.A novel solution of the Possion equation was established and the general analytical solutions of temperature field and thermal distortion field of laser slab were obtained.Then,by taking the Nd∶YAG slab as a model,the distributions of temperature field and thermal distortion field were analyzed.And the temperature fields of Nd:YAG slab under different pump powers and coupled radii were quantitative studied by considering on design requirements of all-solid-state lasers.Computational results indicate that when the YAG doped with a mass percent of 1.0% of Nd-ion is side-pumped by a diode bar with output power of 30 W,the Gaussian spot radius coupled on the side-face of laser slab is 150 μm,and the slab can get a maximum temperature rise of 102.3 ℃,and the maximum thermal distortions of 1.54 μm and 2.66 μm on the side-face and the end-face,respectively.This analytical solution of temperature field can improve the low precision of the numerical analysis method in research of diode laser side-pumped laser slab interior temperature field,and also can be used to analyze other thermal problems in laser systems.