The invention relates to an environment-friendly snow-melting agent and a method for preparing the snow-melting agent by using an amino acid fermentation liquid. The main components of the snow-melting agent include organic acid ammonium salt, amphoteric amino acid ammonium sulfate salt, ammonium sulfate and urea. The method comprises the following steps: using a residual liquid after extracting amino acid from the amino acid fermentation liquid or whey protein hydrolysate as a raw material; firstly conducting concentrating; then conducting decolorization of the concentrated solution; conducting filtration; adding the urea in the obtained filtrate; neutralizing a product with ammonium hydroxide until pH of the product is 7-8 to obtain a viscous fluid; conducting spraying granulation with a fluidized bed to obtain the snow-melting agent. The snow-melting agent has low snow melting temperature, is easy to dissolve and has zero damage to the environment, the biodegradation is complete, and the problem of soil salinization caused by a conventional inorganic snow-melting agent is avoided. The preparation method is simple to operate and low in cost.