Allergic purpura nephritis (also known as “purpura nephritis”) refers to damage to the kidney organ tissues caused by allergic purpura. Clinically, purpura nephritis is diagnosed when hematuria and/or proteinuria appear during the course of allergic purpura (including within 6 months of the disease). The incidence of purpura nephritis in allergic purpura: about 30% to 60% in terms of urinary changes, but nearly 100% if the renal histopathological changes are taken into account. Purpura nephritis is a common disease in pediatrics, according to domestic reports after acute nephritis, nephrotic syndrome, and ranked third. It is also the most common secondary glomerular disease in pediatrics.