Moderate conentration and well-distributed F centers were created in Li-Na doped KCl crystals through diffusion. Hg lamp was used for the centers conversion and FA (II)-FB (II) centers were obtained. Absorption spectrum of the crystal was measured at 77 K, in which double-peaks structure was displayed obviously. Luminous spectrum of FB(II)-FA(II) centers was measured at the same temperature. The luminous peaks of FB(II)-FA(II) centers are at 2.49 μm and 2.66μm respectively. Using the point ion model and taking into consideration the contribution of the seeond-nearest ions in the ion size correction, the unperturbed state of FA(Li) center in KOI crystal was obtained. Then energy level of FA center was oaloulated using perturba-iion method. The result is satisfactory compared with, the experiment data.