The invention discloses a boron compound surface modified perovskite thin film method and an application thereof. By introducing a boron element, non-coordinated iodide ions in a perovskite thin filmcan be passivated effectively, defect mode density is lowered and photoelectric performance of the perovskite thin film is improved, so that an efficient and stable perovskite solar cell device can befurther realized. The solar cell device with a boron compound modified perovskite light absorption layer obtains relatively high photoelectric conversion efficiency; and the preparation method is simple and convenient, the production period is relatively short, and high stability is achieved.