In order to solve the thermal effect problem of laser slab by diode bar side-pumped

temperature modeling of laser slab was investigated. By the analysis of working characteristic of laser slab

a thermal model according to the practical situation was introduced. Based on the heat conduct theory

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. This analytical solution not only solved the problem of calculation error in temperature field caused by the assumption of radial heat flow in laser slab

but also overcame the problem of low precision induced by the numerical analysis method. The results show that when the yttrium aluminum garnet doped with a mass percent of 1.0 % of Nd-ion is side-pumped by a diode bar with output power of 30W

and the Gaussian spot radius coupled on the side-face of laser slab is 150μm

the slab can get a maximum temperature rise of 102.3 oC，1.54μm maximum thermal distortion on the side-face and 2.66μm maximum thermal distortion on the end-face. The temperature field distribution of Nd:YAG slab under different pump power and coupled radius were quantitative studied. The results can be applied to the design of resonant cavity in diode bar side-pumped slab lasers and offer theoretical basis for reducing the thermal effect in laser systems.