When the organic-inorganic hybrid perovskite has been regarded as the gain medium in lasers, the lasing devices with nanosecond laser pulses or continuous wave pumping at room temperatures is unstable and the electrically driven lasing is difficult to be achieved. Gold nanoparticles solution and PEDOT∶PSS solution were blended, gold nanoparticles with size of 20 nm were doped into PEDOT∶PSS interface layer in a slab waveguide device. As a result, the facile device doping with gold nanoparticles shows a 5.5-fold enhanced amplified spontaneous emission intensity than the device without gold nanoparticles. The results show that gold nanoparticles can effectively improve the absorption of CH3NH3PbBr3 film, increase the population inversion and accelerate the excitons radiative decay process. Combining with theoretical simulation, the comprehensive near- and far-field surface plasmon of gold nanoparticles could both couple with the absorption/emission area, so that the amplified spontaneous emission of planar waveguide are improved. The results can provide a reference in fabricating the high performance optically pumped amplified spontaneous emission devices.