Organo-lead halide perovskite has emerged as a promising optical gain media.However,continuous efforts are needed to improve the amplified spontaneous emission(ASE)even lasing properties to evade the poor photo-and thermal instability of the perovskites.Herein,we report that simply through the coating of polymer layer,the CH3NH3PbBr3 polycrystalline films prepared by a modified sequential deposition process show remarkably enhanced photoluminescence and prolonged decay lifetime.