Allergic purpura is a relatively common microvascular allergic hemorrhagic disease. Its causes include infections, food allergies, drug allergies, allergies due to pollen, insect bites, etc., but the cause of allergy is still difficult to determine. It is more common in children and adolescents. The clinical features are mainly skin petechiae, mostly around the joints of the lower limbs and buttocks, and the purpura is symmetrically distributed, appearing in batches, varying in size and color, and may fuse into patches. It usually fades within a few days, but can recur. Platelets are generally quite numerous. It is not difficult to distinguish from idiopathic thrombocytopenic purpura, which is not higher than the skin, asymmetric distribution and reduced platelet count. The rash of allergic purpura is easier to distinguish if it is accompanied by angioneurotic edema, urticaria or erythema multiforme. Patients with allergic purpura may have gastrointestinal symptoms, such as paroxysmal colic or persistent dull pain in the abdomen; joint pain; renal symptoms, such as proteinuria and hematuria, mostly seen in children. Severe cases may be accompanied by gastrointestinal bleeding and renal impairment; treatment includes trying to find out the cause of allergy and avoid it; using antihistamines such as benadryl, promethazine, ankylamine, paracetamol, etc. and glucocorticoids, etc. In the acute stage, allergic purpura should be bed rest and less activity, because activity can accelerate blood circulation and aggravate bleeding; in the remission period, often participate in physical exercise to enhance physical fitness, prevent colds, should actively remove the foci of infection, prevent upper respiratory tract infection, should avoid all allergens, prevent and control the triggering factors of the disease.