Potassium Dihydrogen Phosphate (KDP) doped with l-aspartic acid has been grown by solvent slow evaporation technique from a mixture of aqueous solution of KDP and 0.7% of l-aspartic acid at room temperature. The grown crystals were characterized by powder X-ray diffraction, UV–visible, FTIR analysis. The doping of aspartic acid was confirmed by FTIR spectrum. The Nonlinear optical property (SHG) of l-aspartic acid doped KDP has been confirmed. Microhardness studies were carried out on the grown crystal.