The invention provides an austenite stainless steel erosion agent and a preparation method and application thereof. Ethyl alcohol serves as a solvent of the erosion agent. The solvent comprises, by per liter, 60-120 ml/L of concentrated nitric acid, 150-300 ml/L of concentrated hydrochloric acid and 100-200 g/L of ferric chloride. According to the austenite stainless steel erosion agent provided by the invention, the erosion agent is a novel erosion agent obtained through repeated exploration in the experimental process, the adverse effects of the high volatility and corrosivity of aqua regia on a human body are avoided, the situation that dotted spots are produced due to uneven corrosion through a hydrochloric acid FeCl3 water solution and the other erosion agents, and the erosion process is easy to control; in addition, a polishing effect is achieved to a certain extent, tiny scratches on the surface of an austenite alloy sample can be removed, and austenite grain boundaries and the precipitated phase morphology can be clearly and completely shown; moreover, compared with other common erosion agents, the austenite stainless steel erosion agent is stable in component, capable of being stored for a long time under an airtight condition and high in using convenience.