In this paper an organic solar cell by P3HT: PCBM polymer active layer with gold and silver Nano rods within active region, with Finite Different Time Domain method has simulated. Also the mechanism of Nano rods effect on enhancement of absorption, current density and near field parameters has studied. We will demonstrate that due to the increasing in near field and scattering surround the Nano rods, absorption and current density will increase alternatively. Also we investigate an optimum absorption and current density for various periods of Nano rods in active region.