Gastric cancer is a common digestive system cancer worldwide. Helicobacter pylori (Hp) infection-related gastritis is a major risk factor for gastric cancer occurence. The risk of gastric cancer occuring in Hp infection is related to the factors of microbial flora in the stomach, immune function and environment. In recent years, studies found that gastrointestinal micro-ecology is closely associated with gastric cancer development. In this paper, the following several aspects to gastric cancer were discussed， including the relationship between Hp and cancer of the stomach, the stomach micro ecological change in cancer, roles of the stomach micro ecology in the cancer development, as well as with the interaction between Hp and probiotics for the cancer prevention. The roles of microenvironment in gastric cancer were analyzed for reference for the clinical treatment of the disease.