A single-pass high-gain 1.9 μm fiber gas laser, based on vibrational stimulated Raman scattering in a hydrogen-filled hollow core photonic crystal fiber, is reported. Efficient conversion to the first-order vibrational Stokes wave of 1907 nm is obtained in a low loss negative curvature hollow core fiber with a length of 6.5 m, which is filled with high pressure hydrogen pumped with a linearly polarized 1064 nm microchip pulse laser. The maximum power conversion efficiency, which is more than 27% at 2.3 MPa hydrogen pressure, and a quantum conversion efficiency of 48% are achieved. The maximum laser average power is about 10 mW，and the maximum peak power is more than 2000 W. It provides a potentially effective method to obtain broadly tunable mid-IR fiber lasers of high power and narrow linewidth.