Abstract: Multi-energy spectrum imaging with photon counting detectors has become the focus of X-ray imaging. In this study, the Geant4 simulation software was used to generate the energy spectrum of the ray source, obtaining high-low energy spectra of different ranges by setting different detector energy resolutions and changing the energy threshold. High-low energy projection data of scan objects were obtained for dual-energy reconstruction. The standard deviation of the effective atomic number and electron density under each group were compared. The results show that the higher the energy resolution and the greater the difference between high and low energy spectra, the better is the imaging quality. The energy threshold influenced the imaging accuracy when the spectrum overlap ratio was changed. When the spectrum overlap became smaller and the spectral width became narrower, noise increased, making it necessary to balance the relationship between spectrum overlap and noise to achieve better imaging results.