The invention discloses a preparation method of a vertically-arranged boron nitride nanosheet film and a material with the surface provided with the vertically-arranged boron nitride nanosheet film. The method comprises the following steps: mixing cheap boron oxide powder as a boron source with metal iron powder and magnesium powder, carrying out ball milling for 0.5 h or more to prepare a reaction precursor, taking metal , ceramic, silk screen, and porous ceramic as deposition substrates, heating to 1200-1300 DEG C in a high-purity ammonia atmosphere by using a tubular atmosphere protection annealing furnace, and carrying out heat preservation for 1-8 h, so that a layer of off-white BN nanosheet film is deposited on the surface of the substrate, the contact angle of the film to water is 144-146 degrees, and the hydrophobic property is good. The invention can be applied to the fields of self-cleaning surfaces, self-lubricating surfaces, metal protection, oil-water separation and the like, especially high-temperature corrosive environments. The preparation process is simple, the reaction conditions are mild, and the used raw materials are boron oxide powder, iron powder, magnesium powder and ammonia gas, are cheap, easy to obtain, non-toxic and harmless, and are suitable for large-scale industrial production.