A mid-infrared Ho-doped fiber laser localized at 3 μm band is achieved using the all-fiber 1150 nm fiber laser oscillator as the pump source. The Ho-doped fiber adopts a linear cavity structure which consists of a high-reflectivity golden mirror and a vertical-cutted fiber tip. A 4.5 m Ho:Pr co-doped dual cladding fiber is used as the gain media. The core diameter is 10 μm and the numerical aperture of the fiber core is 0.2. When the 1150 nm pump power is 1.43 W, the mid-infrared fiber laser output is 115 mW. The optical-to-optical conversion efficiency of the Ho-doped fiber laser is 8.0%. The central wavelength is 2868.4 nm under the maximum output power and the full width at half maximum is 1.3 nm. The research results can make a contribution to the further development of mid-infrared Ho-doped fiber laser.