Deoxynivalenol （DON），as a trichothecenes metabolite produced by Fusarium，widely exists in grains including wheat，rice and corn，which seriously threatens human health.Therefore，based on the theoretical guidance of biochemistry，immunology and materials science，we constructed a chemiluminescent fiber optic immunosensor for the on-site rapid detection of DON in grains by using a combination of biosensing recognition and chemiluminescence technology.At the same time，a portable sensing platform for detecting the chemiluminescence signal was integrated into a black light-proof cassette of 32 cm×15 cm× 25 cm，and the weight was less than 3 kg.The results showed that Fourier transform infrared， energy dispersive spectrometry and atomic force microscopy confirmed the successful preparation of fully antigenicized fiber probes. In addition， the constructed chemiluminescence optical fiber immunosensor had a good linear relationship between 0.1-1 200 ng/mL，with the detection limit of 62.7 pg/mL.The functionalized optical fiber probe can be stably stored for 30 days and has good specificity and anti-interference.The recovery rate of DON applied to grain samples was 81.00%-107.33%，and the relative standard deviation was less than 8.69%.Compared with ELISA，the sensitivity of this method was increased by 30 times，and the linear range was broadened by 3 orders of magnitude，indicating that it is suitable for the on-site rapid detection of DON in grain samples.