Green synthesis of nanoparticle is a unique method to synthesis nanoparticles by using biological sources. In this present study spent tea leaves extract was used synthesizing of AgNPs. Synthesizing of AgNPs was confirmed by changing their color to dark brown due to surface plasmon resonance (SPR) phenomenon. Process parameters such as AgNO3 concentration (molarity), extract volume percent, sunlight exposure time and temperature were studied.UV-Vis spectroscopy showed the SPR peaks for AgNPs were between370-435 nm using spent tea leaves extract. Atomic force microscopy (AFM) showed the average particle diameters of AgNPs were between 66 - 117 nm using spent tea leaves extract. Atomic Absorption Spectroscopy (AAS) showed the maximum extraction efficiency was 47% using spent tea extract.