The invention discloses an all-optical fiber broadband flat intermediate-infrared super-continuum spectrum light source. The light source is characterized in that the light source comprises a thulium-doped mode-locked fiber laser module used for generating ultra-short pulses, a thulium-doped fiber amplification module used for generating high-power and high-order soliton pulses, a 2-3 micron high-power SC spectrum generation module used for generating 2-3 micron high-power SC spectrum laser, a silica fiber and chalcogenide fiber efficiently-coupled and encapsulated module and a 2-5 micron intermediate-infrared broadband flat SC spectrum generation module for generating a 10dB-bandwidth coverage 2-5 micron intermediate-infrared band broadband flat SC spectrum, wherein the thulium-doped mode-locked fiber laser module, the thulium-doped fiber amplification module, the 2-3 micron high-power SC spectrum generation module, the silica fiber and chalcogenide fiber efficiently-coupled and encapsulated module and the 2-5 micron intermediate-infrared broadband flat SC spectrum generation module are arranged sequentially. According to the light source, quartz optical fiber tapering and lens optical fibers are used in a matched manner, so that efficient coupling of quartz optical fibers and chalcogenide optical fibers can be realized, and pumping efficiency can be improved, the high-quality full-optical fiber broadband flat intermediate-infrared SC (super-continuum spectrum) light source can be realized; since the light source is of a full-optical fiber structure, the intermediate-infrared SC spectrum light source has the advantages of low cost, high conversion efficiency, high-quality output beams and simple and compact structure.