The growth of LiNbO_3 single crystal with Er~ 3+/Zn~ 2+ co-doped by the bridgman method and the characteristics of absorption spectra and fluorescence spectra were reported. By means of the optimized conditions such as growth rate of 0.8～1.5 mm·h~ -1, temperature gradient about 30～35 ℃·cm~ -1 across the solid-liquid interface and sealed platinum, large size crystals containing Zn~ 2+ (3%) and Er~ 3+ (0.6%) with good optical quality were obtained. X-ray diffraction and DTA were used to characterize the crystals. The results indicate that the concentration of Er~ 3+ ions in crystals decrease along the growth direction, the absorption intensity and the fluorescence intensity of Er~ 3+ ions also decrease along the growth direction. However, for the upper part crystal, the upconversion fluorescence intensity is higher than that of the lower part crystal excited with 800 or 970 nm pump. The effects of crystal lattice, structure defect and effective segregation of Er~ 3+ ions were discussed in respect to the variations were discussed of upconversion fluorescence intensity. The growth of LiNbO_3 single crystal with Er ~ 3 + / Zn ~ 2+ co-doped by the bridgman method and the characteristics of absorption spectra and fluorescence spectra were reported. By means of the optimized conditions such as growth rate of 0.8 ~ 1.5 mm · H ~ -1, temperature gradient about 30 ~ 35 ℃ · cm ~ -1 across the solid-liquid interface and sealed platinum, large size crystals containing Zn ~ 2+ (3%) and Er ~ 3+ (0.6%) with The results indicate that the concentration of Er ~ 3 + ions in the crystallization decreases along the growth direction, the absorption intensity and the fluorescence intensity of Er ~ 3 However, for the upper part crystal, the upconversion fluorescence intensity is higher than that of the lower part crystal excited with 800 or 970 nm pump. The effects of crystal lattice, structure defect and effective segregation of Er ~ 3+ ions were dis cussed in respect to the variations were discussed of upconversion fluorescence intensity.