Helicobacter pylori (H.pylori) infection is the most important pathogenic microorganisms associated with the development of chronic gastritis, peptic ulcer and gastric mucosa-associated lymphoid tissue lymphoma (MALT) in children. H.pylori infection may occur in early childhood and last a lifetime even directly affecting the health of adulthood unless H.pylori infection was eradicated. This article aims to review the infection condition, infection pathway and immunological characteristics of H.pylori and its relationship with extragastroduodenal diseases in children.