The present disclosure provides a fluorescent nanomaterial and a preparation method and applications thereof, and the preparation method comprises: subjecting amphiphilic molecules in a solvent system to an illumination treatment and/or a heat treatment to obtain fluorescent nanomaterials. The preparation of fluorescent nanomaterials provided by the present disclosure is simple in process, simple and easily available in raw materials and requires neither additional addition of a strong acid, a strong alkali, a passivating agent and the like, nor high temperature and high pressure in the preparation process. The whole process is environmentally friendly and pollution-free and the products can be used in various fields.