The design of four spectrum imaging of a single sensor spectro-imaging system was presented. The prism was placed before lens set, departure at different direction of the objective radiation across prism, the separate spectro-image was formed at different place of focal plane. The F number of the spectro-imaging system whose working wavebands are 8.2-8.6 μm, 9.4-9.8 μm, 10.6-11.2 μm and 11.2-12.2 μm is 4, the focal length is 55 cm and the aperture diameter is 50 mm. The spot diagram diameter is less than 40 μm. Vignetting was introduced to solve the superimposition between different spectrum. The aberration characteristic and the blur circle diameter distribution of the system was analyzed. The analysis results showed that the system had a good image quality and met with spectro-imaging requirements.