The invention belongs to the field of production of industrial salts, and especially relates to an energy-saving metal sodium salt, and a preparation method and an application thereof. The method comprises the following steps: screening common metal sodium salt to remove large-granule salts and powdery salts, and uniformly mixing the screened metal sodium salt with sodium fluoride, sodium acetate and other assistants according to a certain mass ratio to obtain the novel metal sodium salt. The content of SO<4><2-> of the novel metal sodium salt prepared in the invention is lower than 0.02%, the above product can be used as a special raw material salt of industrially produced metal sodium to reduce the eutectic temperature of a ternary system and a binary system which are used for preparing the metal sodium by 5-20 DEG C and improve the electricity conductivity by 1-5%, and the method has the advantages of simple process, convenience in operation, no pollution to the product or environment, low cost, and suitableness for large-scale industrial production.