With the development of technology, the traditional single-energy X-ray computed tomography (CT) imaging technology can′t meet the modern industry needs of functional imaging for substance distinction and identification because of the inconsistency between the projection acquisition process and the reconstruction assumption. A multi-spectrum CT imaging method based on energy spectrum filtering separation in view of photon counting imaging detector is presented. Spectrum filtering separation is realized by filtering at X-ray source and monochromatic projection sequence is gotten by various energy imaging. Then an EM-TV algorithm is used at the condition of low dose. By this method, mult-spectrum imaging is realized to meet the demand of substance distinction. Simulation result, which aims at components whose densities are similar, shows that this way can meet the requirement of component discrimination.