To study the thermal conduction characteristics of different doped YAG and GGG laser crystals, the thermal conductivity of different doped YAG and GGG laser crystals generated at 273-393 K were measured by making use of instantaneous measurement method. The temperature field model of the experimental sample was established and the function of thermal conductivity to temperature was educed. The obtained conductivity to temperature curves almost conformed to the experimental results. The experimental results show that the thermal conductivity of the laser crystal decline with temperature, the thermal conductivity of YAG laser crystal declines when adding Yb ions, and the thermal conductivity of the GGG laser crystal declines with the rising of the doped Nd ions concentration. Finally, the experimental results were theoretically explained.