Aiming at the blank and urgent application needsof infrared hyperspectral imaging data,aspacebornedual band infrared hyperspectral imaging scheme is proposed to obtain images with high spatial resolution,high spectral resolution and high temperature sensitivity.The working spectrum covers 3～5μm (MWIR)and 8～12.5μm(LWIR).The spectral resolution of MWIR and LWIR is 50 nm and 100 nm,respectively.The spatial resolution is 60 m,the imaging width is 60km,and the noise equivalent temperature differencesis less than 0.2 K.In this paper,the optical system specifications of the spaceborne dual band infraredhyperspectral imagerare analyzed and determined.Moreover,the telescope optical system,the spectral imaging optical system and the overall optical system are designed.The off axis three mirror design schemewithfree form surface is adopted in the telescope optical system to realize the design of low distortion and high telecentricity under large relative aperture.The relative distortion of the telescope optical systemis less than 0.135%.The Wynne Offner structure is used in the spectral imaging optical system to achieve the design of high imaging quality,low smile and keystone.The MTF of the spectral imaging optical system is close to the diffraction limit under different wavelengths.The design results show that the optical system of thespacebornedual band infraredhyperspectral imager has excellent imaging quality and reasonable structural layout that has strong engineering application value.