The invention provides an application of mitoxantrone and salt thereof as a lymph tracer (such as hydrochloric acid mitoxantrone, oxalic acid mitoxantrone, sulfuric acid mitoxantrone, phosphoric acid mitoxantrone, acetic acid mitoxantrone, citric acid mitoxantrone and the like). The mitoxantrone and salt thereof can be used for preparing injection, powder injection, emulsion, liposome, nanoparticle, microballoon and the like. The mitoxantrone and salt thereof not only can be used for killing malignant tumor cells, but also the blue dye feature can be used as the lymph tracer applied to lymphadenectomy in cancer operative treatment, which is suitable for treating stomach cancer, breast cancer, intestinal cancer, cervical carcinoma, testis cancer and the like.