The absorption and magnetic circular dichroism spectra of f-f transitions 6H15/2 → 6F3/2, 6F5/2 , 6(F7/2 +H5/2) and 6(F9/2+H7/2) in Dy3+ ion were studied in the glasses: Dy2O3-P2O5-SiO2-GeO2 and Dy2O3-La2O3-Al2O3-B2O3-SiO2-GeO2 with different concentrations of Dy3+ ions in temperature range 100-300 K. Basing on this data, absolute values and temperature dependences of the paramagnetic magneto-optical activity (MOA) of the transitions were determined. The origin of the MOA of f-f transitions was analyzed with the help of two models. In the first model, MOA is considered as a consequence of admixture of states with opposite parity by odd components of crystal field. The second approach is based on the Judd-Ofelt theory. The same f-f transitions reveal different values and temperature dependences in different glasses, what testifies to a different symmetry of the nearest environment of Dy3+ ions in these glasses.