The invention discloses a spectral imaging system adopting a variable-diameter fiber field-of-view divider to realize a large field of view. The spectral imaging system comprises a front telescopic optical system, the variable-diameter fiber field-of-view divider and a spectral light splitting system, wherein the front telescopic optical system is used for completing collection of large field-of-view spectral information at a focal plane thereof; the variable-diameter fiber field-of-view divider comprises multiple sets of input terminal fields of view, multiple sets of output terminal fields of view and a variable-diameter fiber bundle; a large-size linear field of view of the front telescopic optical system is divided to multiple sets of the input terminal fields of view and regrouped inthe multiple sets of output terminal fields of view, and the multiple sets of output terminal fields of view are connected with the spectral light splitting system; and the spectral light splitting system is used for performing image field of view splicing on spectral imaging bands of the multiple sets of output terminal fields of view, so as to form the complete large field-of-view imaging spectral information. The spectral imaging system can perform optical division and regrouping on the large field of view to form small field of view groups, reduces the requirements of the large-size linearfield of view for the size of a spectral detecting system, and facilitates the miniaturization of the light splitting element and detector elements as well as the integration of the spectral imagingsystem.