With increase of capacity in wavelength-division multiplexing(WDM) transmission systems,a novel Er~(3+)-Yb~(3+) co-doped double cladding fiber(EYDCF) has received more attention,which has better properties than conventional Er~(3+) doped fiber.In this paper,EYDCFs for application in amplifier were designed and fabricated,and the principles of EYDCF have been analyzed.Absorption of the EYDCF is(20.6 dB/m) and(16.8 dB/m) at 1 530 nm and 980 nm respectively.FWHM in 980 nm is 200 nm.28.8 dBm output power was obtained with a pump wavelength of 980 nm and a pump power of 2 W,which is higher than conventional EDF.The nonlinearity of EYDCF was restrained by decrease of fiber length.