In this paper, the DNA/Cu2O-GS nanostructure was simulated to detect polycyclic aromatic hydrocarbons (PAHs) and compared with our experimental results. We use a simulation for calculations based on density functional theory (DFT). In the first step, DNA/Cu2O-GS nanostructure was simulated and adsorption mechanism, the density of states and charge transfer process were investigated in the presence and absence of PAHs using the QUANTUM ESPRESSO software and BoltzTrap computing code. The simulation results showed that Cu2O-GS nanostructure can be well used to adsorption and stabilization of DNA. Also the simulation results of electrical conductivity change showed that DNA/Cu2O-GS nanostructure can be well used as a field effect transistor (FET) to detect PAHs. On the other hand, the electric current changes of the DNA/Cu2O-GS-FET for three samples of PAHs (benzene, toluene, and naphthalene) were experimentally studies. Also current leakage, the sensitivity, and dynamic range of transistor for benzene, naphthalene and toluene experimentally were investigated. The experimental results show that the DNA/Cu2O-GS-FET can use as a biosensor for PAHs. Our simulation and experimental results are in good agreement and this DFT-based simulation idea can use for other biosensors.