The crucial role of the impact of divalent europium doping in perovskite solar cells is investigated in this work. We selected europium (Eu2+, 117 pm) to replace lead (Pb2+, 119 pm) because their ion radii are really comparable. This appropriate substitution has shown great potential to achieve high stability and enhance the power conversion efficiency of the solar cells. Through adjusting the doping concentration of europium, the perovskite solar cells corresponding average efficiency greatly increased. Furthermore, compared with the CH3NH3PbI3 perovskite film, the attenuation of power conversion efficiency of europium doped perovskite film slowed down 4.7 times at room temperature. Therefore, we put forward a useful method for the optimization of organic–inorganic perovskite solar cells.