Since Helicobacter pylori was identified in early 1980's, evidences accumulated reveal that infection with Helicobacter pylori could cause gastric ulcer, chronic inflammatory of gastric mucosa and increased the risk of gastric cancer. Because the risk for gastric cancer attributable to Helicobacter pylori infection is as high as 40—60%, anti-Helicobacter pylori is a critical strategy in primary prevention of gastric cancer, particularly in the high-risk population. The epidemiology, biology, therapy of Helicobacter pylori infection and gastric cancer prevention by eradication of Helicobacter pylori are reviewed in this article.