A high-precision temperature-controlled narrow band-stop fiber Bragg grating (FBG) filter and light source self-calibration technique are proposed for application in the Brillouin optical time domain reflectometer (BOTDR) sensor system. With the proposed application, the BOTDR sensor system maintains good long-term stability and temperature precision through the reduction of the center wavelength drift in the FBG filters and corresponding decrease in the changes in light intensity. The experiment result shows that temperature precision of 1°C and temperature stability of 0.7°C can be achieved in a temperature sensor over a range of 8 km.