Abstract: The interaction between the temperature field and the laser field plays a crucial role in solid-state lasers. In this paper, the optic-thermal coupling in the diode pumped solid-state lasers(DPSSL) is investigated. From the point of view of microcosmic physics, the thermal transition of particles at upper laser level makes heat generation of the laser crystals depend on the shape of the laser beam, while the laser field is influenced by the temperature in terms of thermal partition of doped particles. These effects, together with the usual thermal-optic effect of a fluctuation of the refraction index induce by uneven temperature distribution, lead to a complicated coupling between the laser field and the temperature field. It is shown that the optic-thermal coupling plays an important role