The QKD system has a rigorous demand on the stability of the optical source,especially the stability of the wavelength and the intensity of the laser,which directly affect the system′s bit rate.To meet this requirement and consider the temperature characteristics of DFB Laser,an effective temperature control system was designed.The system uses FPGA as the controller,along with the incremental PID algorithm to monitor the working temperature of DFB laser in real time and uses thermoelectric refrigeration control chip MAX8520 as the TEC driver.The NTC thermistor,which is integrated into the DFB laser,constitutes a temperature acquisition module and a closed-loop negative feedback structure.The experimental results show that the temperature control accuracy is above ±0.03 ℃,and the wavelength drift can be controlled within 0.01 nm.The temperature control system has the characteristics of small size,high efficiency and high reliability.It can provide a stable temperature control for the laser to ensure the stability of the optical source wavelength of the QKD system.