The invention discloses a preparation method for reducing down feather loss rate. The method includes the steps: removing impurities in raw down feather, washing and drying the raw down feather, adding nano-silver, uniformly mixing mixture, and treating the mixture by microwaves to obtain a pre-prepared material a; mixing ferric chloride hexahydrate, ferrous chloride tetrhydrate and water, heatingand stirring mixture, adding ammonium hydroxide to uniformly stir mixture, adding humic acid, adjusting temperature to stir mixture, adding stone needle powder to stir mixture, centrifuging the mixture, removing upper solution, drying a lower solid material, and crushing the solid material to obtain a pre-prepared material b; mixing the pre-prepared material a, the pre-prepared material b, composite biological enzymes, rose essential oil, surface active agents and water, and heating, stirring, filtering, washing and drying mixture to obtain high-whiteness down feather. According to the method, on one hand, the fiber strength of the prepared down feather can be enhanced, the is reduced, on the other hand, adhesion among down feather protein fibers can be effectively avoided, bulkiness of the prepared down feather is effectively maintained, and deodorization and sterilization effects are good.