Fuente: WIPO "industrial hemp" The invention provides a method for preparing carbon quantum dots based on industrial hemp, the carbon quantum dots and application of the carbon quantum dots. According to the invention, industrial hemp is taken as a raw material, and two kinds of carbon quantum dots with different particle sizes are prepared by using a one-time hydrothermal carbonization method and are respectively used for detecting Fe and tetracycline antibiotics. Compared with a respective preparation mode in the prior art, the preparation method has the advantages that an environment-friendly and pollution-free natural product industrial hemp is selected as a carbon source, the industrial hemp is pretreated and then subjected to a hydrothermal carbonization reaction with ultrapure water, a reaction solution is dialyzed in a dialysis bag, liquid outside the dialysis bag is further dialyzed again in dialysis bags with different molecular weights, and the purity of the product is improved. According to the present invention, two different sizes of carbon quantum dots are obtained, the prepared carbon dots have good optical stability, the preparation process is simple and rapid, and the industrial hemp is low in cost, such that the cost is reduced, and the problem that the industrial hemp straw is difficult to treat is solved.>