A single-ended fiber coupled actively acousto-optic Q-switched all-fiber laser with high-repetition-rate, short pulse duration, narrow line-width and high efficiency is experimentally demonstrated. Based on the combination of fiber grating and plane mirror providing a linear Fabry-Perot (F-P) cavity, the fiber laser is working on the backward-pump scheme by use of laser diode and (2+1)×1 pump coupler, achieving all-fiber structured pulse ytterbium-doped double-clad fiber laser by adopting single-ended fiber coupled acousto-optic modulator (AOM). AOM operates in the first direction and inversely outputs, inverted output Q-switched pulse with repetition rate of 20~100 kHz adjustable. At the repetition rate of 50 kHz and pump power of 5.7 W, laser system outputs highly efficient, stable, narrow line-width short pulse of 2.64 W average power, corresponding to single pulse energy of 528 μJ, pulse duration of 56 ns and peak power of 943 W. The center wavelength of laser is around 1080 nm with line-width of 0.06 nm, and the optical-optical conversion efficiency is as high as 46%.