Erythema nodosum is one of the more common rheumatic diseases, mostly in young women aged 20-40 years, with a long course and recurrent attacks, easy to occur in spring and autumn. The clinical features are red or purple inflammatory nodules located on the posterior surface of the lateral surface between the knee and ankle, ranging from bean to walnut size, nodules are elevated on the skin, if the site is deeper, they can only be touched but not revealed, they can appear in batches and symmetrically, the nodules are hard and painful when pressed, the local skin is hot, and disappear after a few weeks without leaving traces, most of them are accompanied by joint pain and muscle pain, and a few of them can have joint redness and swelling with restricted movement. The cause of the disease can be caused by infection, drugs, systemic diseases, but there are also unknown causes. Modern medicine believes that the pathology of the disease is perivascular lymphocyte and neutrophil infiltration, inflammatory reaction in the walls of small and medium-sized veins, intimal hyperplasia and partial occlusion of the lumen. At present, western medicine only really treats the primary disease, and those with unknown primary etiology use non-steroidal anti-inflammatory drugs and immunosuppressants, but they have many side effects and are prone to recurrence after stopping. Chinese medicine can eliminate or relieve inflammation by adjusting the organism. 1. To explore the disease mechanism, blood stagnation and obstruction is the root of the disease. There is no name for this disease in Chinese medical literature, but it is similar to “plum nucleus fire dan” in terms of symptoms. The main manifestation of erythema nodosum is a hard subcutaneous nodule that turns from red to purple, and the painful area is fixed and does not move, which is a typical manifestation of bruising. It is caused by external wind and heat, internal dampness and heat, and the flow of wind and dampness and heat into the skin, blocking the meridians and blood stasis. The imbalance of yin and yang qi and blood, the deficiency of righteousness, the susceptibility to external evil, and the inability to expel evil are important factors in the development, regression and prognosis of the disease. According to the differences of external evil, personal constitution, initial recurrence, and long duration of the disease, the method of invigorating blood and resolving blood stasis is applied to treat the disease with good results. It is also used to promote blood circulation and disperse blood stasis; rhubarb to invigorate blood circulation and disperse blood stasis; pollen to subdue swelling and disperse nodules; and chai hu to regulate qi and promote circulation. Modern pharmacological research proves that peach kernel, safflower, angelica, rhubarb and santoprene all have the effect of promoting blood circulation, reducing exudation, reducing inflammatory reaction and promoting inflammation absorption. 2. Discriminatory treatment, with staging as a wonderful method. Professor Wang Yuming treats erythema nodosum with the general purpose of activating blood circulation and removing blood stasis, and emphasizes the identification of the right changes and the appropriate treatment by stage and type. According to the course of the disease and clinical manifestations, Professor Wang divided the disease into five types, which are discussed as follows Heat and toxicity invasion type: the initial stage of erythema nodosum is mostly caused by the internal invasion of wind and heat and toxicity, the evil is depressed in the skin, heat hurts the blood vessels, blood stagnation, and nodules are formed in the skin. Symptoms: Acute onset, nodules are higher than the skin, bright red skin color, burning when touched and painful when pressed. In case of heat toxicity, it may be accompanied by generalized fever, joint pain in lower limbs, swelling, red tongue with yellow coating and slippery pulse. The treatment is to clear heat and detoxify the toxin and activate blood circulation to remove blood stasis. Dampness and heat nodules: external dampness, heat, internal dampness and heat obstruct each other, paralyzing the meridians and forming nodules under the skin. The symptoms are slow onset, nodules gradually increase, heat pain, bright red or purple-red skin color. Dampness tends to block the lower limb meridians and can be accompanied by heavy limbs, soreness and pain in the limbs, swelling of the lower leg especially in the ankle joint, yellow and greasy tongue coating and slippery pulse. Treatment is to invigorate blood circulation and resolve blood stasis, and to clear heat and dampness. Qi deficiency and blood stasis type: the body is deficient, and when it is infected with external evil, it is ineffective in eliminating the evil, and the evil stays in the body, blocking the channels and forming stasis, resulting in nodule formation. Symptom characteristics: nodules slightly above the skin or deep epidermis is not exposed and can be reached by pressing, skin color is light and dark or unchanged, light pain on pressure. Recurrent episodes are accompanied by weakness of the limbs, shortness of breath, fatigue, less color, dizziness and lightheadedness. Treatment is to invigorate blood circulation and eliminate blood stasis, and to benefit qi and promote correctness. Phlegm and stagnation type: Dampness is contained in the heat and decoction into phlegm or dampness in the spleen is deficient, phlegm obstructs blood flow in the veins and channels, blood stops as stasis, phlegm and stagnation are intertwined, blocking the meridians and channels, flowing into the skin, and tangible evil is depressed under the skin to form nodules. Symptoms: nodules are dark in color, do not disappear over time, are not hot to the touch, and are sore and painful when pressed. Phlegm and blood stasis are stuck in the joints, and the blood and qi are not connected, which may be accompanied by soreness and swelling of the joints, tightness and numbness, unfavorable movement, sometimes light and sometimes heavy, coughing phlegm, chest tightness, etc. The treatment is to activate blood circulation and eliminate stasis, and to remove phlegm and turbidity. Cold and dampness stagnation type: the body of Yang deficiency, feeling dampness, dampness from the cold, cold and dampness knotted each other, depressed subcutaneous, blocking Qi and blood to form nodules. The nodules are dark and not hot, slightly higher than the skin or deeper than the epidermis, with cold limbs and cold pain in the joints, aggravated by cold, with long recurrent episodes. The treatment is to activate blood circulation and remove blood stasis, and to warm the meridians.