A spectral calibration facility consisting of a monochromator and a collimator was established to calibrate the Offner imaging spectrometer with a convex grating designed by ourselves. The self-designed software for sampling and processing spectral data was used to calibrate the Offner imaging spectrometer and analyze obtained data. Calibrated results show that the calibration facility has a compact conformation, better commonality and high calibration precision, and its spectral range is better than 400-800 nm and spectral resolution is superior to 10 nm, which can satisfy the calibration need in practice.