The analytical expression of transmissivity and reflectivity of dual fiber Bragg grating (FBG) has been given based on the mode coupled theory, and the gain equations of the pump laser with dual FBG are also obtained. The characteristics of reflection and transmission for dual FBG were analyzed by relevant expression, and the effects of laser gain curve were studied. The dual FBG is composed of a pair of FBGs with the same structure and properties. The spacing of the two FBGs has been optimized to get the best mode-locking characteristics. The output spectral characteristics of the uncooled pump laser with dual FBG or single FBG wavelength locker are practically measured when the operating temperature are 0 ℃, 20 ℃, 70 ℃, respectively. The results show that the output spectral characteristics of the uncooled pump laser with dual FBG have been greatly improved. The uncooled pump laser can work steadily in the temperature range from 0 to 70 ℃. The wavelength shift is 0.2 nm. The side mode suppression ratio is more than 45 dB, and the spectral band width is less than 1.57 nm.