Here in, we report prostate specific antigen (PSA) detection method using DNA aptamer functionalized gold nano disks array. The approach is based on DNA aptamer-PSA specific interaction and the localized surface plasmon resonance (LSPR) extinction max shifts of the transmitted light (UV-Vis). The specific interaction results in a stable dynamic equilibrium. The concentration effect on equilibrium time has been described. We also describe the relationship between the aptamer concentration and the plasmon response. Using 2 nano molar DNA aptamer on gold nano arrays, a detectable linear range from 1.7 ng/mL to 20.4 ng/mL was obtained with the R2 value.