A wart on a child is a common wart caused by human papillomavirus infection, which can be transmitted through direct contact, or indirect contact. The source of infection is the patient and healthy virus carriers, will enter the epithelial cells through the skin mucous membrane tiny breaks, and replication, proliferation, resulting in epithelial cells abnormal proliferation, differentiation, caused by benign redundancy. 1. direct contact: children’s body skin contact with the patient’s warts, or through the hand scratch warts, and then contact with normal skin, easy to cause common warts. 2. Indirect transmission: the child’s skin contact with the patient’s contaminated clothing, bed linen and other household items, may also cause cross-pollination, caused by the child’s body with common warts.