At 320c by using Ethyl alcohol is used as the solvent by the method of slow evaporation technique is adopted and a pure transparent solid organic crystal of Silver Nitrate Thiourea Urea (SNTU) was obtained. The optical property of the crystal was carried out by UV-Vis spectral study. The functional group was identified by FTIR spectral analysis. The crystals structure was characterized by XRD analysis .The thermal stability of the crystal was evaluated by thermo gravimetric and differential thermal analysis (TG-DTA). The microhardness also confirmed the stability of the crystal by the Vickers method.