In this paper, the intermediate field energy matrices of the double-valuedgroup for d3 configuration are derived. The relationship among the crystal structureparameters, the ZFS parameter D and the splitting △E(2E) of the 2E state inCr3+:A12O3 laser crystal are established. On the basis of the hypothesis of thecrystal lattice distortion, the ZFS parameter D, Zeeman g factor, optical finespectra, and the splitting △E(2E) of the 2E state are calculated, the obtainedresults are in good agreement with experiment data reported in the literatures. Theresults show quantitatively that the six O2- ligand moves towards the central Cr3+ion by O.OO325 nm, meanwhile, the front three O2- of the Cr3+ rotate O.286° toward[111] axis while the back three O2- rotate 1.118° toward it.