The invention provides a pressure-assisted high-quality perovskite film preparation method, which belongs to the technical field of photovoltaic film preparation. The method comprises the steps that first, a perovskite precursor film is prepared on a substrate; then, two substrates with perovskite precursor films are oppositely placed, so that the perovskite precursor films are closely attached together; pressure is applied on the top film; the bottom film is annealed by heating to slowly grow a perovskite crystal; and after the annealing is completed, the substrate with the perovskite film onthe top is removed to acquire the high-quality bottom perovskite film. According to the invention, the perovskite film prepared by the method has the advantages of micron-sized grains, microsecond-level carrier lifetime, high crystallinity, few grain boundaries, and low defect state density; the optoelectronic performance and long-term stability of the perovskite film are effectively improved;and the performance of a device is improved accordingly.