The invention provides a povidone-iodine film-forming disinfectant, which comprises the following components by weight percentage: 5% of povidone-iodine, 0.1-0.5% of Carbomer, 1-10% of PVP and 0.1-0.5% of potassium iodate. The invention also discloses a preparation method and application of the povidone-iodine film-forming disinfectant. After long-term placement, the povidone-iodine film-forming disinfectant provided by the invention has a stable effective iodine content and pH, and is free of layering after long-time placement, the solution has good liquidity, and can form a layer of disinfectant protective film capable of disappear spontaneously, and can effectively prevent cow mastitis.