Stomach cancer is the number two cancer killer in the world, causing 600,000 deaths each year, and China is one of the regions with high incidence of stomach cancer. In recent years, the incidence of gastric cancer has a clear trend of rejuvenation. In the past, the majority of gastric cancer cases were in the age group of 40 to 60 years old, but nowadays, the incidence of gastric cancer is more in the age group of 35 to 55 years old, and the incidence rate of gastric cancer among young people aged 19 to 35 years old has been on the rise in recent years. In addition to genetic and immune function decline, the occurrence of gastric cancer is also closely related to dietary and hygiene habits. There are 7 kinds of improper dietary habits and hygiene habits that can cause “cancer from mouth”: i. frequent intake of too much salt-pickled food, such as pickles, sauerkraut, pickled fish, etc.; ii. fondness for smoked and baked food, such as bacon and grilled meat skewers, etc.; iii. frequent consumption of unfresh food, such as moldy food, expired and spoiled canned food, food with excessive preservatives, etc.; iv. Fourth, less fresh fruits and vegetables, resulting in nutritional deficiencies and decreased resistance; Fifth, low-protein diet to reduce the repair capacity of the gastric mucosa; Sixth, overeating, preferring dry, hard, hot and spicy food, eating too fast, etc.; Seventh, smoking and alcohol abuse. Some of these bad habits can lead to H. pylori infection, which is an important factor related to the occurrence of gastric cancer; some of them can make certain carcinogenic chemicals enter the body or directly destroy the gastric mucosa; others, such as smoking, alcoholism and eating too hot food, can directly destroy the gastric mucosa, leading to the occurrence of gastric ulcer and chronic gastritis, which can evolve into gastric cancer in the long run. It is difficult to change the genetic factors of gastric cancer, but it is possible to change the poor hygiene and dietary habits, so as to reduce the incidence of gastric cancer.