A kW-class ytterbium-doped all-fiber laser is built based on the single cavity structure.The effects of several different parameters of gain fiber length,coiling radius and cooling temperature on the output laser characteristics are studied experimentally.After parameters optimization,the final selection of ytterbium fiber length is 16 m,the coiling radius is 6cm,and the cooling temperature is 25℃,and 1135 W continuous laser output is realized when the pump power is 1348.3 W.The center wavelength of the laser is 1080 nm,the light-to-light conversion efficiency is 84.2%,and the slope efficiency is 87.7%,the beam quality M2 is 1.2,achieving a quasi-single-mode output.And the laser has a power instability of 1.4% in 72 h continuously work.This experimental study has certain guiding significance for the research of high power fiber lasers.