The invention relates to the field of medicines, and in particular relates to a medicinal magnetic plaster for treating tumors. The plaster comprises a medical adhesive tape, more than 20 traditional Chinese medicines, a medicinal magnetic layer made of a permanent magnet or magnetic powder, a protective layer and the like. The medicinal magnetic plaster has the effects of dredging collaterals, removing stasis, eliminating phlegm, promoting diuresis, removing toxicity to relieve pain, relieving and eliminating mass and the like to inhibit tumor growth, changing shapes of cancer cells, inducing apoptosis of tumor cells, gradually reducing tumors, eliminating inflammation of vascular wall, controlling transfer of pain signals, improving local micro-circulation, controlling spread and pain of medium or advanced cancer, and the like; the plaster can be divided in different magnetic field strength, different shapes and different specification models; when the plaster is used, the required specification model is selected, the protective layer is peeled off, the medicinal magnetic layer of the stagnation-eliminating plaster is directly adhered to the meridian skin, corresponding acupoint or the Shenque acupoint in a range of the focus area, and the plaster is fixed by the medical adhesive tape; different parts can be adhered by multiple plasters at the same time, and each plaster is used for 1-2 days.