Nominal glass compositions x mol%(Li₂O) (30-x) mol%(Na₂O) 65mol%(B₂O₃): 5mol%(Sm₂O₃) where x=(0, 10, 20 and 30) mol% have been prepared by the conventional quenching melt annealing technique. The optical constants (α, n, k), optical energy gap (E_g), Urbach energy tail (∆E), linear refractive index (n₀), nonlinear refractive index (n₂), linear optical susceptibility χ⁽¹⁾ and the third order of non- linear optical susceptibility χ⁽³⁾ have been calculated before and after 8MRad γ- irradiation. The analysis of the absorption coefficient data revealed the existence of an allowed indirect transition both before and after γ- irradiation. It was observed that the value of optical energy gap depends on the value of lithium content (x). E_g increases from (3.15eV- 3.3eV) and from(2.93 eV -3.09eV) before and after γ- irradiation respectively when lithium content value (x) varies from 0 to 20 mol% then decreases to 3.24eV and 2.85 eV at 30 mol% of lithium content before and after γ-irradiation respectively. ΔE decreases from 0.1193 eV to 0.095 eV and from 0.565 eV to 0.401 eV with increasing lithium content from 0 to 20 mol%, then increases to 0.114 eV, 0.512 eV at 30 mol% of lithium oxide respectively before and after gamma irradiation.  The linear and nonlinear optical parameters have been estimated from the obtained values of n and E_g. It was found that n₀, χ⁽¹⁾, n₂ and χ⁽³⁾ vary from (2.32-2.35), (0.35- 0.363)esu., (24.1-27.71)x10^-12&(1.48-1.73)x10^-12esu.when lithium content value varies from 0 to 30 mol% before γ-irradiation respectively. The parameters n₀, χ⁽¹⁾, n₂ and χ⁽³⁾ are found to vary from (2.37-2.63), (0.368-0.473), (29.332-71.626)x10^-12& (1.846-5.001)x10^-12esu.afterγ-irradiation respectively. The variation in optical band gap and Urbach energy are due to the variation in the glass structure.