Purpura in children, also known as hemorrhagic capillary poisoning, is an allergic reaction caused by different factors. It manifests as microvascular metabolic hemorrhage, distributed on the skin surface in multiple, symmetrical, batched skin bruises, so it is also known as allergic purpura in children. The allergic cause of purpura in children is difficult to determine, infection, food, medicine, pollen, insect bite, etc., can be the cause of allergy, so finding allergens and avoiding contact as much as possible is the main means to prevent reoccurrence. The bruises on the skin vary in color and can fuse into patches, which will fade within a few days and then recur. The treatment of purpura in children should be carried out in a regular public hospital. In addition to finding allergens, the main focus is on anti-allergy, if accompanied by complications, symptomatic medication is needed according to different conditions to avoid aggravation of the disease repeatedly.