Abstract: The coupled transport of neutron and fluorescence （E≤100 eV） through the scintillating fiber array （SFA） was simulated using the Monte-Carlo code Geant4 for analysis of fluorescence characteristic of square plastic SFA. The relation between the intensity distribution of fluorescence and the incident neutron’s position was analyzed, and an equivalent position to calculate SFA’s modulation transfer function was found. The fluorescence intensity distribution and gathering efficiency combined with the recorded visible photon for a lens-coupled system were included in the evaluation, and an approximate expression between the modulation transfer function of SFA and the sampling function was discussed. It is found that modulation transfer function of SFA can be got by transforming the energy deposition distribution of planar scintillator.