In order to obtain high power, high beam quality and high efficiency of solid-state lasers, by means of theoretical analysis, the models of temperature distribution and cooling rate of slab laser mediums were established. A lamp-pumped Nd∶glass slab solid-state laser was taken as an example for numerical calculation. The results show that, the temperature distribution and cooling rate of slab solid-state lasers can be more accurately described by the 2-D model. This research has certain guiding significance for the design of high power slab laser mediums.