The Potassium di hydrogen phosphate (KDP) is a well-known dielectric inorganic nonlinear optical (NLO) material in tuned laser applications. Since most of the amino acids exhibit NLO property, it is of interest to dope them in KDP to increase their application. In the present study optically good quality crystal of pure and amino acid (L-phenylalaine, L-methionine and L-glutamic acid) doped KDP have been grown from low temperature solution growth technique using water as a solvent. The crystalline nature of the grown crystals is characterized by powder X-ray diffraction and single crystal X-ray analysis, it reveals that the crystal belongs to tetragonal system. The presence of various functional groups of pure and amino acids doped KDP crystals were identified by FT-IR analysis, the UV-visible spectrum shows an improvement in the optical transmittance and it is used in optical sensors. The second harmonic generation (SHG) efficiency of amino acids doped KDP crystals were found and compared with pure KDP crystals.