Abstract: The sensitivity for a scintillatingfiberarray ne ut ron detector is studied. The energy response of the detector to neutrons a nd gamma rays is simulated using MonteCarlo method. The calibration work is ca rried out at several specific energies as well. The results show that the tenden cy of the theoretical energy response curve is in good agreement with that from the experiment. By fitting the experiment data, the energy response of the detec tor in a wide energy range could be obtained. The detector's neutrontogamma sensitivity ratio is about 5.3 for the 2.5 MeV neutrons and 1.25 MeV gamma rays.