Objective To observe the multi-detector spiral CT manifestations of primary gastric lymphoma. Methods Multi-detector spiral CT findings of 21 patients with pathologically confirmed primary gastric lymphoma were retrospectively analyzed, the lesions' site, extent, thickness of gastric wall, the enhancement pattern, the situation of gastral cavity and gastric mucosa, and the encroachment of perigastric lymph nodes and other organs were observed. Results Tumors in all 21 patients were non-Hodgkin lymphoma. Multiple lesions were found in 19 patients, while single lesion was detected in 2 patients. CT demonstrated irregular thickening of the gastric wall (8-62 mm) in all 21 patients, including diffuse thickening (n=10), segmental thickening (n=9) and local thickening (n=2). Homogeneous enhancements were found in 19 patients, and lamellar inhomogeneous necrosis were found in 2 patients. Intact mucosal lines were found in 12, and destructed mucosal line in 9 patients, while obscure serous membranes were found in 2, and distinct serous membrane in 19 patients. The stomach showed distensible without significant narrow in 12 patients. The enlargement of perigastric lymph nodes were found in 6 patients. No hepatic encroachment was found. Conclusion Multi-detector spiral CT manifestations of primary gastric lymphoma are relatively specific, and multi-detector spiral CT shows high value for the diagnosis of the disease.