The present invention relates to a production method of calcium formate, specifically discloses a preparation method of feed grade calcium formate, comprising the following steps: a. Putting light calcium carbonate or nanometer calcium carbonate into water or mother liquor, adding mass concentration ≥ 88 % formic acid solution; b, solid-liquid separation of the reaction product; c, dry calcium formate solid. The advantages of the present invention are: 1) the temperature of the reactor can be raised rapidly, and the temperature can be effectively avoided from being too high, no external heat source and forced heat exchange are required to reduce the temperature, energy consumption is reduced, the production process is simplified, and the product quality is stable; 2) the product is naturally separated, The reaction time is shortened, and the impurity content of the product is reduced; 3) It is beneficial to the growth of calcium formate crystals, further improving the product purity, and the product has a large crystal structure, uniform particle size, and good appearance.