The invention relates to an additive for an electro-deposited bright ferro-nickel alloy. The additive comprises a brightener and a complexing agent. The brightener comprises the following components: N-propargyl cyanamide, n-propargyl cyanamide salt, N-propargyl dicyandiamide, N-propargyl dicyandiamide salt, bis-N-propargyl dicyandiamide and bis-N-propargyl dicyandiamide salt; the complexing agent comprises the following components: amino acetic acid, amino acetate, aminopropionic acid, aminopropionate, diphosphonic acid and diphosphonate. By means of a synergistic effect of alkynyl and nitrile functional groups, the propargyl-containing cyanamide compound has very good brightening and leveling effects if being used in a ferronickel plating solution; the ferronickel plating coating can be prevented from flooding and fogging effectively by means of double complexing action of amino acids such as amino acetic acid and aminopropionic acid and diphosphonic acid and salt compositions thereof.