The invention discloses a nontoxic diluted-magnetic quantum dot material with fluorescence and room temperature ferromagnetism, and a preparation method thereof. The quantum dot material is Co: CuInS2 coated by two to four layers of a ZnS shell and has a structural formula of Co: CuInS2@ZnS, wherein Co exists in quantum dots in the form of ions. The preparation method comprises the following steps: (1) preparation of a Co: CuInS2 core with room temperature ferromagnetism; and (2) injecting a Zn source at room temperature and wrapping the core with a proper thickness of the ZnS shell layers. The preparation method adopts a single-pot thermal decomposition process, is simple in process, easy to operate, convenient in raw material supply and cheap in raw materials, can be completed in a common chemical laboratory and is easy to promote.