The present invention relates to the field of laser frequency-mixing technologies, and in particular, to an all-fiber laser frequency mixer and a frequency-mixing fiber laser thereof. In the all-fiber laser frequency mixer and the frequency-mixing fiber laser thereof, a graded index fiber coupling technology is used to implement an all-fiber laser frequency mixer, and the all-fiber laser frequency mixer is further combined with a fiber laser to implement an all-fiber frequency-mixing fiber laser. The apparatus can implement all-fiber frequency doubling, sum frequency or difference frequency on any one or two of the following linearly polarized narrow linewidth fiber lasers: a 1 μm fiber laser, a 1.5 μm fiber laser, a 1.9 μm thulium-doped fiber laser, a 2 μm thulium holmium co-doped fiber laser, a Raman fiber laser, and a frequency-mixing fiber laser and implement an all-fiber fiber laser covering ultraviolet, visible, near-infrared, mid-infrared bands.