The xNb2O5-(15-x)La2O3-40B2O3-45BaO (x=5, 7.5, 12.5 mol%) glasses doped with Eu3+ ions in 1 mol% are fabricated by the melting method. The Fourier transform infrared (FTIR) spectra, phonon side-band spectra, emission and excitation spectra of the glasses are measured. The crystal field parameter and coordination number of Eu3+ ions in the glasses are obtained according to the splitting of their 5D0-7F1 levels. The intensity parameters 'Omega'2 and 'Omega'4 of Eu3+ ions for optical transition are calculated from their emission spectra in terms of reduced matrix U(t) ('lambda'=2, 4, 6) character for optical transitions. The results indicate that the intensity parameters 'Omega'2 and 'Omega'4 increase with the increase of Nb2O5 content, suggesting that the symmetry becomes lower, the band of Eu and O atoms becomes stronger and the covalence increases with the increase of Nb2O5 content.