Abstract: Helicobacter pylori(H.pylori) is one of the most common pathogens which is closely associated with chronic gastritis,peptic ulcers,intestinal epithelium metaplasia,gastric carcinoma and MALT.H.pylori takes the form of spiral.It has flagellae and many gene isoforms.The infectious rate of it in the global population has reached 50% and is more in the patients with chronic gastritis or peptic ulcers.The main source of infection of H.pylori is mankind.H.pylori can be spread through the way of mouth to mouth,stool to mouth and medicine.The etiological factors of H.pylori  include virulence factors,cellular factors,immunological factors,heredity susceptibilities of bodies.To recognize the propagation process and pathogenic  mechanism of the H.pylori has a vital significance in the prevention and therapy of it.

Key words: H.pylori, epidemiology, etiological factors