The invention discloses a nucleolus target fluorescence carbon point which is made of the following raw materials in parts by mole: 10 parts of m-phenylenediamine and 1-100 parts of cysteine. The invention further discloses a preparation method and application of the nucleolus target fluorescence carbon point as a nucleolus fluorescence probe and a cell nucleus target anti-cancer medicine carrier. Compared with the prior art, the product disclosed by the invention is excellent in nucleolus target imaging performance, nucleolus target medicine carrying function, fluorescence property, anti-light bleaching property, biocompatibility and good water dispersity and stability. Meanwhile, the preparation method is simple, raw materials are cheap and easy to obtain, and large-scale preparation is achieved.