The invention relates to a low-toxicity and environmentally friendly gold and silver oredressing additive as well as a preparation method and application thereof. The main raw materials of the additive comprise sodium hydroxide, sodium carbonate, urea and potassium ferrocyanide. The preparation method comprises the following steps of: heating the sodium hydroxide, the sodium carbonate, the urea and the potassium ferrocyanide to 600-1,000 DEG C, and after the materials reach a molten state, continuing to preserve heat for 1-2 hours; directly cooling to normal temperature; and demoulding to obtain a nubby gold and silver oredressing additive. The product of the invention can be widely applied to producing noble metal mines, such as soaking, core spraying, and the like of gold oxide mines, silver oxide mines, copper oxide mines, and also can be used for industrial production industries of electroplating, and the like for replacing highly toxic sodium cyanide chemicals. Compared with other non-toxic sodium cyanide drugs, the additive provided by the invention has the advantages of good effect, stable drug properties, environmental friendliness, lower cost, and the like.