The invention belongs to the optical field, and particularly relates to a spectral imaging method and a spectral imaging device realized by means of multiple slits. According to the method and the device, through setting a multi-slit assembly at a primary image surface of a frontend imaging mirror, the spectral images of a plurality of objects are simultaneously obtained. By means of push brooming, multiple times of imaging are performed on one object, spectral information of one object in multiple data frames can be superposed, thereby improving the effective energy of the object by times and furthermore increasing a signal-to-noise ratio of the image. The spectral imaging method and the spectral imaging device effectively settle the defects of insufficient energy and low signal-to-noise ratio in a high-resolution imaging spectrometer.