We present a design of tunable grating filter based on high-precision temperature control. We use aluminum groove to encapsulate the grating so that it is insusceptible to strain. Then we design a high-precision temperature control module composed of 3 pieces of temperature control chips MAX1978 working in parallel to monitor and control the temperature of aluminum groove, thus achieving the long-term stability of center wavelength of the tunable grating filter. The temperature accuracy can reach 0.1 ℃, with the dynamic range of 10 ℃~40 ℃ continuously adjustable. The tunable grating filter based on this temperature control module can reach 0.0016 nm wavelength stability at center wavelength. The experimental results confirm the configuration′s feasibility.