The &OHgr;tintensity parameters (t=2,4,6) of Er3+ions in several oxide glasses and the isomer shift (IS) of151Eu Mo¨ssbauer spectra in glasses of the same composition were determined. Among these &OHgr;t’s, the &OHgr;6parameter was found to have a good relation with IS; &OHgr;6decreases with an increase of IS which reflects the 6selectron density of rare‐earth ions. From the theoretical expression of &OHgr;t, &OHgr;6is considered to be more affected by the overlap integrals of the 4fand 5dorbitals than &OHgr;2and &OHgr;4, and to increase with an increase of these overlap integrals. These overlap integrals are supposed to decrease when the 6selectron density is larger, since the 6selectron density shields the 5delectron orbital.