For the purpose of improving precision and practicability of Fiber Optic Gyroscope, the thermal fabrication of SLD module was analyzed and a detailed description of the all-digital control system had been carried out.The testing result indicated that in a temperature range of -15℃ to 55℃,it restrained the temperature fluctuating of SLD.This technology yielded a much better stability of SLD′s wavelength 0.014% and output power 0.4%,which conduced to a much better performance of FOG.