Abstract: In order to analyze the temperature characteristics in the stimulated emission of a CTH:YAG laser, taking the quasi-three-level characteristics of CTH:YAG and the influence of Tm-Ho quasi-thermal equilibrium system into account, a so-called relative oscillation efficiency parameter was defined based on the photon density in the rate equation. The numerical simulation results show that relative oscillation efficiency is a nonlinear decreasing function of temperature, and there is a stop temperature at which the stimulated emission can not happen. The stop temperature is in direct proportion to the energy stored by Tm-Ho quasi-thermal equilibrium system, and relative oscillation efficiency also augments with the stored energy rising. The analysis provides a theoretical evidence of the temperature characteristics of CTH:YAG, and is useful for optimizing the output pulse.