The photosensitivity of a low-loss As2S3 chalcogenide glass fiber core under 532 nm near-bandgap light irradiation is experimentally investigated. The experimental results show that at the beginning of light irradiation, the photo-induced refractive index change of the fiber core first decreases rapidly towards the negative direction, and then recovers and increases gradually towards the positive direction with the extension of irradiation time. As for these two processes, the time duration and the refraction index change value are determined by light irradiation power. As the irradiation power increases to a certain threshold value, the photo-induced refractive index change shows a positive increment in the recovery process, and the refractive index change can be increased to about 3×10 -3 with the further increases of irradiation power and exposure time. In addition, the As2S3 fiber Bragg grating is experimentally fabricated and its central wavelength occurs blue shift-recovery-red shift during exposure. At the same time, the experimental results also disclose that the optical stopping phenomenon with a cut-off efficiency of about 55% is observed in the As2S3 fiber under near-bandgap light irradiation.