The design and the development tract of Basic Health Insurance System for Urban Residents（BHISUR）took example by Basic Health Insurance System for Employees（BHISE）to a great extent，such as choosing serious illnesses for outpatient benefits. As a result，the serious illnesses for outpatient benefits in BHISUR didn’t pay enough attention to Children’s illnesses. Taking example for some inherited metabolic diseases to discuss choosing children’s serious illnesses for outpatient benefits，this article analyses the problems of the security of the children’s serious illnesses for outpatient services and proposes how to perfect it in BHISUR.