The invention discloses a dual-wavelength and same repeat-frequency intermediate infrared ultrashot-pulse all-fiber laser source, and belongs to the technical field of intermediate infrared laser. 2.8-micrometer laser passes through a light combiner, a fluoride fiber, a first gain fiber and a tapered fiber and is input to the light combiner to form a first annular cavity so as to generate first mode-locked pulse, 1.7-micrometer and the first mode-locked pulse are input to a second gain fiber to generate second mode-locked laser and third mode-locked laser, the 2.8-micrometer laser and the third mode-locked pulse are input a third gain fiber to generate fourth mode-locked pulse and fifth mode-locked pulse, the wavelengths of the third mode-locked pulse and the fourth mode-locked pulse are equal, and the third gain fiber outputs dual-wavelength same repeat-frequency laser. By the dual-wavelength and same repeat-frequency intermediate infrared ultrashot-pulse all-fiber laser source, the problems that an intermediate infrared super-continuous spectrum source system in the prior art is complicated and high-strength ultrashort-pulse laser output is difficult to achieve at an intermediateinfrared band with the wavelength exceeding 3.5 micrometers can be solved.