The invention provides a fertilizer coating sustained-release film, a coated sustained-release fertilizer and a preparation method and application of the fertilizer coating sustained-release film, andrelates to the technical field of sustained-release materials. The fertilizer coating sustained-release film comprises a first coating film, a second coating film and a third coating film which are arranged in sequence from inside to outside, wherein the first coating film is mainly prepared from chitosan, the second coating film is mainly prepared from nano silica and/or hydrated lime, and the third coating film is mainly prepared from carboxymethylcellulose and calcium chloride. The provided fertilizer coating sustained-release film not only can achieve the controlled release of granular nutrients of the fertilizer, but also has good compatibility with soil, is easy to degrade, cannot cause environmental pollution, and can also improve the soil, increase the soil pH value, and ensure the sustainable development of agriculture.