In order to research high-power multi-position-pumped fiber lasers,the theoretical analysis was presented based on the rate equations and boundary conditions of Yb-doped double-clad fiber lasers. All-fiber laser is built with the self-made cascaded couplers. In the experiment,the pump efficiency of a single coupler is 96%,pump transmissiom loss is 10%,signal loss of the couplers are 0.87 dB and 0.18 dB respectively. In the structure of linear cavity,the optical conversion of forward pump is 69%,lower to the backward pump of 70% optical conversion,consistent with theoretical simulations; in the two-end pump,single input pump power of 975 nm is 110 W,the output power is 311 W with the central wavelength of 1 080 nm,spectral width is 1.6 nm,the optical-optical conversion is 70%,M2～1.3. The results have shown that the output power of laser will continue to increase with the increase of the pump power or the number of couplers.