The design,fabrication and properties of the ytterbium-erbium co-doped double-cladding fiber are reported,which is made by method of a combination of the MCVD and solution doping technique.By comparing the concentration of Erbium ion and ytterbium ion and improving the manufacture technique,the optimal concentration ratio of the Yb3+/Er3+ is gotten,and the two kinds of doped ions′concentration are improved.Furthermore,the depressed center of perform is avoided,and the satisfying double-cladding erbium-ytter...