The present invention discloses a multichannel broadband high-resolution spectrograph, comprising a plurality of light source incident slits, a multichannel integrated grating, a multichannel shared two-dimensional focus imaging mirror and a two-dimensional area array detector which are sequentially disposed along a light source incident or reflection line, wherein the multichannel integrated grating consists of a plurality of sub-gratings, incident light enters the corresponding integrated gratings along the light source incident slits and then is focused by the shared two-dimensional focus imaging mirror after diffraction of the integrated grating, and diffraction light in a full-spectrum region is incident onto a focal plane of the two-dimensional area array detector for detection. No any mechanical displacement part is disposed, multichannel, full-spectrum and high-speed detection and analysis is achieved, and the present disclosure has high spectrum resolution and working reliability.