The crystal structure of N-[2,4,5-Trichlorophenyl] acetamide is optimized through semi-empirical method by Austin Model 1 (AM1) together with restricted Hartree-Fock closed shell wave function to describe the influence of interactions on crystal packing using MOPAC2009 program. The electric dipole moment (μ)and molecular hyperpolarizabilities (β and γ)are computedbytime dependent Hartree Fock (TDHF) method to inspect the non-linear optical behaviour of the material. The UV-VIS spectral study of material in 300-1100 nm wavelength range shows a wide transparency window which is the key requirement for the non-linear optical (NLO) property of the material. The experimentally measured value of second harmonic generation efficiency is 0.8 times to that of reference material potassium dihydrogen phosphate (KDP). The intramolecular charge transfer interaction results during the HOMO-LUMO transition observed from molecular orbital calculations.