Abstract: THe 3d radical wave function of Fe²⁺ ions proposed by Zhao and the calculating method of the ligand-field transition of Fe²⁺ ions of M 1 site in the crystal structure of diopside used by Xue were adopted in this paper.The calculated results show that there are three spin-allowed spectra of Fe²⁺ ions of M 1 site.The calculated energy of 9767cm^-1 among these is in reasonable agreement with energy of stronger band 9718-9633cm^-1 observed in the optical spectra of jadeite.