New organic non-linear optical (NLO) material L-histidine Meta nitro aniline (LH-mNA) has been grown by slow evaporation solution growth technique at 450C temperature. High optical quality and appropriate size of crystals were grown under optimized growth conditions. The grown crystals were yellowish color and transparent. UV-Visible transmission spectrum shows 99% transmission of light in the entire visible region and cut-off wavelength was occurs at 268 nm. The optical band gap was calculated to be 4.62 eV. With the help of optical data to be calculate absorption coefficient (α), extinction coefficient (k), refractive index (n), dielectric constant (ε), optical conductivity (σop). Photoluminescence study provides information of discrete levels of energy states, which is show that material emits the different colors of wavelength in different regions. The crystalline nature of grown crystal was confirmed by powder X-ray diffraction analysis (XRD). Scherer formula calculates particle size and lattice strain. With the help of XRD data make the W-H plot, which is provide particle size and lattice strain.