Gastric cancer ranks fourth in morbidity for malignant cancers worldwide. As a major tumor the factors affecting its incidence rate have always been focused. Many scholars believe that the decline of gastric cancer morbidity is most probably related to various factors such as life and diet habits. This paper mainly analyzes four aspects ①The reduction of Helicobacter pylori infection rate is usually matched with the decline of morbidity and mortality of gastric cancer ②The dose-response relationship between salt intake and incidence rate of gastric cancer has been fully supported by the literature ③As the duration of smoking increases the risk of cancer significantly increases ④For many years vitamin C has been considered an important factor in reducing the risk of gastric cancer. More influencing factors are still being explored and as we deepen the understanding of gastric cancer it will be of greater help to doctors and patients in the diagnosis treatment and prognosis of the disease.