The invention discloses rare earth-carbon dot-nucleoside white-light emission hydrogel as well as a preparation method and an application. The preparation method comprises the following steps: preparing a carbon dot aqueous solution, a europium nitrate aqueous solution, a terbium nitrate aqueous solution and a nucleoside aqueous solution; uniformly mixing the carbon dot aqueous solution, the europium nitrate aqueous solution, the terbium nitrate aqueous solution and the nucleoside aqueous solution, adjusting pH with ammonia water, heating the mixture to react, and cooling a product to the roomtemperature to obtain the rare earth-carbon dot-nucleoside white-light emission hydrogel. The preparation process of the rare earth-carbon dot-nucleoside white-light emission hydrogel is convenient and simple. The color of fluorescence of the hydrogel can be adjusted conveniently with the method. The rare earth-carbon dot-nucleoside white-light emission hydrogel has multiple responses to externalstimulation, can show different colors and hydrogel states in response to pH, temperature, ions and the like and is environmentally friendly.