In the gas concentration measurement based on tunable diode laser absorption spectroscopy (TDLAS), higher temperature stability of laser is required. To meet this requirement, an automatic temperature control (ATC) proposal is put forward. A mathematical model of the thermoelectric cooler (TEC) is derived. The thermal inertia of TEC is tested and the proportional-integral-derivative (PID) control circuit parameters are determined. Finally, a temperature control circuit with high control performance is designed. The closed negative feedback loop was adopted for the circuit. PID circuit is used to generate control signal and drive the TEC. High accuracy controlling of VCSELs working temperature is realized. The results show that the temperature stability is up to ±0.03℃. The temperature control circuit could effectively keep the laser working stable.