To improve the spectral calibration accuracy of an imaging spectrometer and to reduce the complicity of the calibration process, the idea of the cross-spectral calibration was proposed based on the calibration principle of monochromator scanning. Then, a cross-spectral calibration system was designed for a monochromator and an imaging spectrometer. The spectral calibration experiments for the monochromator and the imaging spectrometer were performed and the spectral calibration data were processed. The experimental results show that the accuracy of the spectral calibration for the monochromator is better than ±0.1 nm , the spectral range of the imaging spectrometer is greater than 400-800 nm and its spectral resolution is better than 3 nm. The cross-spectral calibration system overcomes the defect that the spectral calibration for the monochromator and the imaging spectrometer requires two detectors, and the calibration is implemented by switching the calibration modes only.It offers higher calibration accuracy for both the monochromator and the imaging spectrometer,and has the merits of low complexity, versatility, wider range and high calibration accuracy.