Space-based atmospheric remote sensing urgently requires wide field-of-view differential optical absorption imaging spectrometer. The research objective is spaced-based atmospheric trace gas differential optical absorption imaging spectrometer with wide covering range and minor volume and mass. Based on the research objective, a wide field-of-view unabscured telecope is designed using an off-axis two-mirror system and a relay system. An optical system of space-based wide field-of-view differential optical abdorption imaging spectrometer is designed using the wide field-of-view telescope and an Offner spectral imaging system. The field of view of hyspectral imager is 60°× 0.24°, relative-aperture is 1/3, and working waveband is from 280 nm to 450 nm. Ray tracing and optimization are performed by Zemax-EE software. The root mean square (RMS) spot radius for different wavelengths are less than 5 mm for the Offner spectral imaging system. The spectral resolution is 0.692 nm, and the requirement of specification is no more than 1 nm. The modulation transfer function (MTF) for different wavelengths of imaging spectrometer is more than 0.67 at characteristic frequency in the spatial direction. The design results satisfy the requirements of imaging quality, and are suitable for the application of space-based remote sensing.