The producted reason of the nephelauxetic effect is investigated.The dependent factors of the effect are showed to be the i (ionic characters of the bond)

M(coordination numbers) and R(the bonding average length between the central metallic ion and the ligands).Also

the conditions of producted the nephelauxetic or contra-nephelauxetic effects are showed. The law of displaced energy levels of the rare earth compounds is discussed and the red or blue displacement of the spectral lines is explained in the solid.