Allergic purpura: It is a systemic disease with necrotizing small vasculitis as the main pathological change, which can involve multiple organs of the body. Clinical manifestations include skin purpura, joint swelling and pain, abdominal pain, blood in stool, and some patients have hematuria and proteinuria, which mostly occur within one month after skin purpura. The cause can be allergic reaction caused by bacterial, viral and parasitic infections, or allergy to certain drugs and food, or caused by plant pollen, insect bite, cold stimulation, etc. Often related to the following factors: 1, infection: 1/3 of cases have a history of upper respiratory tract infection 1 to 4 weeks before the onset of the disease, many patients with recurrent disease is also related to this. 2, drugs: antibiotics, sulfonamide, isoniazid, captopril, etc. 3, food, fish, shrimp and crab, etc., 4, cold stimulation, plant pollen, insect eggs, mosquitoes, vaccination, animal feathers, paint, etc. Allergic purpura affects the prognosis is mainly kidney damage! The typology of renal damage: 1. Isolated hematuria or isolated proteinuria. 2, Hematuria and proteinuria. 3, Acute nephritis type. 4, Nephrotic syndrome type. 5.Acute nephritis type. 6.Chronic nephritis type. Disease treatment Treatment principles Purpura nephritis should be selected according to the patient’s age, clinical manifestations and different degrees of renal damage. Actively control the immune inflammatory response, inhibit glomerular tract proliferative lesions, and prevent and delay the formation of chronic fibrotic lesions in the kidney. General treatment During the active stage of the disease, attention should be paid to rest and maintenance of water and electrolyte balance. Those with edema and large amount of proteinuria should be given low salt, water restriction and avoid high protein food. To prevent recurrence of purpura and aggravation of renal damage, attention should be paid to prevention of upper respiratory tract infection and removal of chronic infectious lesions (such as chronic tonsillitis and pharyngitis). The author has found that many patients have nasopharyngitis, and after nasal flushing, the disease is controlled; actively search for possible allergens and avoid re-exposure. Drug treatment (1) Isolated hematuria or pathology grade I: Only treat allergic purpura accordingly; microscopic hematuria has not been reported in the literature with definite efficacy. Changes should be closely monitored and a minimum follow-up of 3-5 years is recommended. (2) Isolated proteinuria, hematuria and proteinuria or pathology grade IIa: Angiotensin-converting enzyme inhibitors (ACEI) and/or angiotensin receptor antagonists (ARB) class of drugs have a hypoproteinuric effect. Regal polyglucoside 1mg/(kg?d) in 3 oral doses of not more than 60mg per day for 3 months. However, attention should be paid to its side effects of gastrointestinal reactions, liver function damage, bone marrow suppression and possible gonadal damage. (3) Non-nephrotic levels of proteinuria or pathology grade II b, IIIa, nephrotic syndrome or pathology grade IIIb, IV, acute nephritis or pathology grade IV, V, and other three types, require hospitalization to adjust the treatment plan.