Using self-developed side-pumped couplers,a multipoint side-pumped,ytterbium-doped double-clad all-fiber laser was built,and this laser was studied under different types of pumping.In the experiment,cladding optical dissector was added;gain fiber was active fiber of 20/400 μm.The setup didn’t have specific cooling device.When the maximum pump power is 223.6 W,the output power for forward pumping is 152.2 W,and the center wave length is 1080 nm,optical-optical conversion efficiency is 69%;for backward pumping,the output power of 1080 nm is 156.5 W,optical-optical conversion efficiency is 70%.Maximum output power of 311 W is obtained with the pumping power of 443.8 W for double-end pumping;optical-optical conversion efficiency is 70%.