The density calculated decreases with increase of Nb2O5 content from 5.680 g cm-3 to 5.493 g cm-3, this means that , the glass matrix becomes less dense, It was found that , the optical energy gap decrease, but the refractive index increase by increasing Nb2O5 content . The electronic polarizability of oxide ion decrease with decreasing the optical basicity. The value of optical basicity shows that the glass materials are less basic. It is suggested that by increasing Nb2O5 content , the glasses become less polarized. Also, It was found that the values of third order nonlinear susceptibility increase by increasing Nb2O5 content and are found to be larger than those of the silica based glasses. The glasses are found to possess a high refractive index (2.170 – 2.213), a comparatively narrow band gap (3.992 eV – 3.785 eV), high electronic ion polarizability (2.445 Å3 -2.546 Å3) and high optical basicity (0.987 – 1.014). It was found that the values of the third order nonlinear optical susceptibility are in the range (0.7604-0.9271)x10-12 esu. Finally, all the above values are a good basis for predicting new non linear optical materials.