Vasculitis is a group of diseases in which inflammation and destruction of blood vessels are the main pathological changes. The clinical manifestations vary and mostly cause systemic damage, so it is also known as systemic vasculitis. There are different subtypes of vasculitis. Depending on the size of the vessels, they are divided into large-vessel involvement, medium-vessel involvement and small-vessel involvement, which correspond to a number of different diseases. Diseases with large vessel involvement, such as large arteritis; diseases with medium vessel involvement, such as polyarteritis nodosa; and diseases with small vessel involvement, such as ANCA-associated vasculitis; are typed according to the cause, such as primary vasculitis or secondary vasculitis. Secondary vasculitis includes vasculitis secondary to diseases such as lupus erythematosus and rheumatoid arthritis, as well as those caused by tumors, infections, and medications. The main symptoms of vasculitis are multisystemic damage, which is divided into systemic and local symptoms. The systemic symptoms are mostly fever, malaise, and joint and muscle pain. Skin damage is manifested as polymorphic erythema, nodules, purpura, papules, etc., most commonly below the knee, and most frequently on the lower part of both lower legs and the back of the feet. Local symptoms vary depending on the organ affected by the vasculitis. For example, aortitis may lead to syncope or cerebral infarction, and polyarteritis nodosa leads to mesenteric artery thrombosis and abdominal pain due to mesenteric ischemia. Renal involvement can result in proteinuria, hematuria, and in severe cases, renal failure. The pathogenesis and pathological basis of different vasculitis are different, and the treatment can be very different, so different diseases should be typed differently by pathology, and then choose a suitable treatment plan for the patient