A simple theoretical method is introduced for studying the interrelation between electronic and molecular structures. By diagonalizing the 120 ×120 complete energy matrices, the relationships between zero-field splitting (ZFS)parameter D and local distortion parameter △θ for Cr3+ ions doped, separately, in α- and β- alums are investigated.Our results indicate that there exists an approximately linear relationship between D and △θ in a temperature range 4.2-297 K and the signs of D and △θ are opposite to each other. Moreover, in order to understand the contribution of spin-orbit coupling coefficient ζ to ZFS parameter D, the relation between D and ζ is also discussed.