Approximate formulas of transient temperature and stress distributions in the slab of a two-side pumped heat capacity laser are attained by solving the heat diffusion equation. Based on the formulas, the distributions of temperature and stress during the pump period of a two-sided symmetrically laser diode array (LDA) pumped Nd:GGG slab laser with 5-kW average output power are numerically simulated. The results show that the temperature in the slab will averagely increase by more than 70 Celsius
