Gastric intestinal metaplasia (IM) is generally believed an intermediate stage in the multistep process of gastric adenocarcinoma, and considered as precancerous lesion. IM has multiple pathogenic factors, and many molecules have been found involved in the mechanisms for its occurrence. Epidemiological evidence showed the possibility of reversibility in IM, but it is still controversial at present. The authors address, in this paper, the research progress in respects of causes, molecular mechanism and reversibility of IM.