By analyzing the offner spectroscopic optical system, an equation to calculate quickly the initial structural parameters is summed . Based on the calculated initial structural parameters we optimized a set of spectral optics used for short-wave infrared (1 000~2 500 nm), which has been designed with large optics aperture (F/# 22), high spectral resolution (better than 10 nm) and long entrance slit (12 mm).Within the entire field of view and wavelength, the modulation transfer function MTF is greater than 05.The complete imaging spectrometer with smaller size and light weight (less than 5 kg). The instrument test results show that the spectral linearity over the whole spectral range is good, and after spectral calibration the wavelength accuracy is more than 4 nm. The resolution tests of different bands shows that the spectral resolution over the full wavelength range is consistent with the design, and dynamic imaging experiments show that the spectral images are clear and the spectral data has good quality.