In recent years, the incidence of gastric cancer has been increasing, and how to use modern medical imaging technology to make correct diagnosis and accurate preoperative staging in its diagnosis and treatment has important clinical significance for the selection of surgical plan, disease follow-up and prognosis. However, it cannot show the depth of tumor infiltration or whether the tumor has broken through the plasma membrane and invaded outward, lymphatic metastasis and distant metastasis, etc. Moreover, some patients still have psychological burden p fear and pressure to undergo endoscopic examination. Conventional CT can detect and display the site, size and morphology of tumor, and roughly determine the invasion range, lymph node metastasis and distant metastasis of tumor, but cannot perform accurate preoperative staging of tumor. With the introduction of spiral CT into clinical application, it has become a new method for localization and preoperative staging of gastric tumors. Gastric cancer is the most common gastrointestinal malignancy. In the past, patients with gastric cancer were often operated after gastroscopy or GI examination alone. The emergence of MSCT technology provides a new reliable means for accurate preoperative staging, avoiding the blindness of surgery, and also provides a new method for postoperative follow-up of patients. It can also provide a control for postoperative patient follow-up, such as observing whether recurrence is observed by changes in MSCT images. The main manifestation of gastric cancer under MSCT is limited or diffuse thickening of the gastric wall, and the gastric wall appears significantly enhanced after contrast injection. Since thickening of the gastric wall is not the only manifestation of gastric cancer, especially some early gastric cancers, we cannot ignore the importance of the enhancement of the gastric wall for the examination of the lesion. Except for a few cases without any manifestation on MSCT, mucosal intensification in the arterial and portal phases of the lesion area, with the submucosa remaining intact, is a characteristic of T1 stage gastric cancer. All layers of gastric wall in progressive gastric cancer have different degrees of thickening. There is still a big controversy about the value of determining metastatic lymph nodes of gastric cancer under MSCT. Currently, some scholars adopt 10 mm lymph node diameter as the criterion to determine the presence of metastasis, while some studies propose 5 mm as the boundary, and metastatic lymph nodes are mostly relatively high density or peripheral high density with low density in the center, or compress blood vessels and have a larger short/diameter ratio (ratio ≥ 0.7). The size and length/diameter of lymph nodes should not be the only reference for determining N-stage, and the enhancement performance of lymph nodes under multi-stage scanning should not be ignored in order to achieve a higher accuracy rate. With the current performance of 16-row spiral CT and the application of multiplanar reorganization (MPR) reconstruction technology, there is still a lot of room for the development of the judgment of each group of lymph nodes, and the accuracy rate can be improved, which requires more in-depth research in this area. In determining whether the lesion invades the pancreas, it is mainly based on the existence and clarity of the fat gap between the stomach and the pancreas. The presence or absence of the fatty layer between the stomach and pancreas is considered as the main basis of whether the pancreas is invaded or not, but when the patient is malnourished or cachectic or even inflammatory adhesions can cause the loss of the fatty layer and affect the performance of the fatty layer under MSCT. Also, MSCT may not detect microscopic infiltration of the tumor. Since most gastric cancers show significant contrast enhancement with CT intensity similar to that of adjacent organs with multiple blood supply such as liver and pancreas, it is also not feasible to identify direct infiltration of gastric cancer with surrounding organs by CT intensity. When the gap between gastric cancer and adjacent organs is parallel or oblique to the scanning direction, partial volume effect makes it difficult to determine the relationship between gastric cancer and adjacent organs.MSCT has higher sensitivity and specificity for distant metastases such as liver, which has rich blood supply and obvious enhancement during enhancement, and its location is relatively fixed and less affected by respiratory motion. The lymph nodes around the great vessels and the posterior peritoneum are clearly shown with significant enhancement. In patients with omental metastasis, the omentum usually appears as a disorganized omental structure like torn cotton wool, and some patients can also see soft tissue shadows. Ovarian metastases from gastric cancer (Krukenberg tumor) can be seen as soft tissue masses in the adnexal region on MSCT. MSCT, as a new examination method, can provide a practical, non-invasive and patient-friendly reliable method for preoperative staging of gastric cancer. If combined with other examination methods, the preoperative staging of gastric cancer will be more accurate and help to choose a more systematic and reasonable treatment plan.