In this paper,the reasons that photose nsitivity in Ge/B doped fiber gratings is higher than that in Ge doped fiber g ratings are analyzed.The effects of hydrogen-loaded on the photosensitivity in Ge/B doped fiber gratings are also studied.The results show that the photosensi tivity in Ge/B doped fiber gratings can be improved after hydrogen-loaded and the photoinduced refractive-index of Ge/B doped fiber pratings exists saturati on during exposed to UV pulses before or after hydrogen-loaded.