Due to their low cost, flexibility, and convenience for long distance data transfer, plastic scintillation fibers (PSF) have been increasingly used in building detectors or sensors for detecting various radiations and imaging. In this paper, GEANT4 Monte Carlo simulation tool was used to obtain some radiation effects of PSF under high-energy neutron irradiation. BCF-20, a plastic fiber material, produced by Saint-Gobain, was used in the simulation. The fiber consists of a core scintillating material of polystyrene and an acrylic outer cladding. Incident neutrons produce energy deposition in fiber through neutron induced recoil proton events. The relationships between energy deposition efficiency and fiber length, fiber radius and incident neutron energy are presented. The variation with those parameters and parameter selection are also analyzed.