Through the proper conditions such as feed materials with proper composition (Li_2O 48.6 mol%, Nb_2O_5 51.4 mol%), growth rate of less than 3 mm/h, a temperature gradient of 20~40℃/cm across the solid-liquid interface and suitable gradient field of the whole furnace,LiNbO_3 crystals co-doped with Cr 3+ ions in 0.1 mol% and Zn in 3 and 6 mol% can grow,respectively, by Bridgman method.The crystals without micro-defects are obtained, and there is no impurity center under the irradiation of He-Ne laser. The emission spectra between 700~1200 nm and the temperature-dependence emission spectra of R lines at 710~740 nm were measured. The observed R lines were attributed to the different Cr 3+ ion sites (Cr 3+_ Li and Cr 3+_ Nb) and the hot phonon-assistant absorption.