Junk food was studied among 1019 children and adolescent in the Haidian District in Beijing. 97.5% had eaten at least one type of junk food and 15.88% of them had eaten all types: deep fried food, pickled food, processed meat products, biscuits, coke or alike drinks, convenience/fast food, canned food, dried or preserved fruit, cold and sweet food, barbecue food. Most of the children and adolescent ate junk food mainly during breakfast at home. Most of the surveyed children and adolescent did not have correct idea on nutrition of junk food.