By means of numerical analysis method,the influences of many factors on output threshold pumped and output powers were analyzed,such as fiber length and back cavity lens reflectivity.These results provide theoretical foundation for optimized design of all-fiber laser device.Yb-doped all-fiber laser device with stable narrowed spectral linewidth laser output was made successfully,using fiber gratings as feedback and frequency-selected cavity lens.Tapered fiber realizes low-loss conncection between pumped module and Yb-doped double cladding fiber,and high effective pumped laser output power transmission.The stable laser output can be gained in this test,of which the wavelength is 1 082.50 nm,spectrometric width is 0.113 nm,the largest stable laser output power is 8.5 W，pumped threshold power is 0.8 W,and slope effectivity is 70.8%.