Abstract: A method for preparing an inorganic perovskite battery based on a synergistic effect of gradient annealing and antisolvent includes preparing a perovskite layer by a gradient annealing and an antisolvent treatment. A thickness of the perovskite layer is 100 to 1000 nm; when preparing a perovskite precursor solution of the perovskite layer, a solvent is an amide-based solvent and/or a sulfone-based solvent; a concentration of the perovskite precursor solution for preparing the perovskite layer is 0.4 to 2 M; and the gradient annealing is conducted at 40 to 70° C./0.5 to 5 min+70 to 130° C./0.5 to 5 min+130 to 160° C./5 to 20 min+160 to 280° C./0 to 20 min; and a solvent for the anti-solvent treatment is an alcohol solvent, a benzene solvent or an ether solvent.