Characteristic gamma rays of 100 keV to about 6 MeV from different elements stimulated by neurons have been applied to diagnosis biological imaging.In this paper.BGO detectors are used for the spectrum simulation.Signals from a single crystal and after correction are both obtained.and the energy spectrum summing adjacent signals seems possible to achieve excellent energy resolution for such high-energy photons.Some ideal suppositions are introduced and some other information,such as spatial resolution and difficult electronics,should be considered after this correction.