An Yb3+-doped lithium silicate glass for multi-graded-index-core fiber is prepared by a two-step melting process. Absorption, emission spectra and fluorescence-lifetime of the samples are measured, and the stimulated emission cross-section σemi of Yb3+2F5/2→2I7/2 transition in samples is calculated by McCumber theory. It is found that σemi of Yb3+ ions in lithium silicate glass at 1006 nm is 0.38×10-20 cm2, and its fluorescence effective line-width is about 82.4 nm, its fluorescence lifetime is 1.31 ms. The Li+-Na+ ion-exchange properties of Yb3+ doped lithium silicate glasses are investigated in molten sodium nitrate at 530 ℃. Imaging properties and radial refractive index profile of gradient index lens made by ytterbium-doped lithium silicate glass before and after central-axis of Yb3+-doped lithium silicate glass rod Li+-Na+-ion-exchanged is studied. Spectral analysis and ion-exchange experimental results show that the glass is an ideal material for production of gradient index laser optical fiber. It can be used for multiple gradient index core fiber. A combination of good lasing and ion-exchange properties enables a new approach to large-mode-area fiber laser.