Mg:In:Fe:LiNbO_3 crystals with various Li/Nb ratios(Li/Nb= 0.85,0.94,1.05,1.20,1.38) have been grown by Czochralski technique.The infrared transmittance spectra,the absorption spectra,photo scattering resistance ability,response time and exponential gain coefficient were measured.The results show that the OH~-absorption peak of the crystal with Li/Nb=0.85 is near 3481cm~(-1),the OH~-absorption peak of the crystals with Li/Nb=0.94、1.05、1.20 moved to 3505cm~(-1),While the crystal with Li/Nb=1.38 have three pe...