In this paper, we investigated the structural, electronic, mechanical and optical properties of Li 4 BN 3 H 10 using the ultra -soft pseudopotential method which is based on the density functional theory (DFT) with CASTEP code. The optimized lattice parameters of Li 4 BN 3 H 10 correlate well with the theoretical calculations and experimental measurements that are currently available. Using elastic constants, the material's stability was verified. Based on the elastic constants, we discovered several mechanical features of the material. Between 0 and 20 eV, optical spectra calculations are made, taking into account the real and imaginary parts of the dielectric function epsilon (omega), reflectivity R(omega), index of refraction n(omega), coefficients of extinction k(omega) and absorption alpha(omega). The dielectric function is wide close to the middle ultraviolet (4.13-6.20 eV). The extinction coefficient of the Li 4 BN 3 H 10 has the ability to worn for implements like Bragg's reflectors, optical and optoelectronic equipments. The optical parameters of Li 4 BN 3 H 10 disclose that our working constructions have an elevated dielectric constant, with a greatest absorption in the visible range holding out over 1.49 x 10 5 cm -1 Li 4 BN 3 H 10 is deemed to be an appropriate material for optoelectronic applications based on calculated optical results. The gravimetric hydrogen storage capacities of Li 4 BN 3 H 10 compound is 11.06 wt %. These promising capacities exceed the 6.5 wt % target set by the US Department of Energy for 2025.