The DFB tunable diode Laser is one of the most important components in the laser spectrum measurement system. The main factors that affect the output wavelength and output power of DFB tunable diode laser are the injection current and operating temperature, and the latter has a bigger effect on the laser. This paper designed temperature control circuit for laser, and analyzed the influence of PI parameters on the temperature control stabilization and short term stability experimentally; the designed temperature control circuit is applied on DFB tunable diode laser for study of longterm monitoring in laser output wavelength and output power, and achieved that standard deviation of the laser output wavelength is 0.2×10-6, the standard deviation of output power is 0.02 mW.