Features of gastric cancer under gastroscopy: 1) the color of mucosa of the lesion area has changed, its color is darker red than normal mucosa and darker; 2) the gastric mucosa of the lesion area is pitted and uneven, looks very irregular, and is not smooth; 3) the gastric mucosa area can be seen through gastroscopy, some parts of which are bulged, similar to gastric polyps, and the early symptoms and signs of gastric cancer are not obvious. There are many kinds of gastroscopy, such as ordinary gastroscopy, painless gastroscopy, and now there is also capsule gastroscopy to assist in diagnosis. Due to bad eating habits and high pressure of life, many people often have stomach discomfort. Helicobacter can also cause problems of gastric ulcer and gastritis. Good dietary habits and regular medical checkups as well as knowledge of diseases are very necessary to know and fundamental to help prevent gastric cancer.