A fast-growing procedure (FGP) to fabricate perovskite films with large grain sizes is described in this article. In the FGP method, the perovskite precursor solution is coated onto the substrates at a temperature of ∼240 °C. The solvent in the precursor solution evaporates quickly in about 2 s, resulting in the rapid formation of a perovskite film without further annealing process. Millimeter-scale perovskite grain clusters are obtained in the film. Based on such perovskite films, fabricated planar heterojunction perovskite solar cells give a power conversion efficiency (PCE) above 8%.