To address the problem of heat accumulation of optical crystals in solid-state lasers and ensure the stability of its work performance, a temperature-control method with high temperature control accuracy and large temperature control range, based on a semiconductor Thermoelectric Cooler (TEC), was proposed. Based on the operating characteristics of the TEC, the heat effect and the heat transfer mechanism of the optical crystal, a temperature-current double closed-loop temperature control model was established. The proposed model controls both the electrical characteristic variations of the working TEC and the temperature variations of the optical crystal. A high-precision and wide-range optical crystal thermostat control system was designed and implemented. Experimental results demonstrate that the overall temperature control accuracy of the proposed system is better than ±0.002 ℃, and the system can quickly stabilize at any set point temperature in a wide temperature range of -15—120 ℃, when the set temperature and the actual temperature deviate 20 ℃, a stable convergence time of less than 60 s, which meets the requirements of solid-state laser optical crystal for temperature range and accuracy.