The purpose of our paper is to simulate and optimize the electro-optical characteristics of a reversed Perovskite planar solar cell. Firstly, the synthesis of the CH3NH3PbI3 was exposed. Then, the absorption, reflection and transmission phenomena were studied. The effects of the thicknesses of CH3NH3PbI (d) and HTL (D) layers on the efficiency of the presented have been simulated. Subsequently, the back contact metals effect on Jsc, Voc, FF and η was taken into account. For a thickness d=0.6µm, the output parameters reached Voc=1.07V, Jsc=22.75mA/cm2 , FF=78% and η=19.02%. Besides, the efficiency is reduced by the defect density at the CH3NH3PbI3/PEDOT:PSS interface more than that at the PCBM/CH3NH3PbI3 interface and it should be less than 1013 cm-3 to have better solar cell performance.