Objective：To evaluate the diagnostic value of 64-row spiral CT in the preoperative TN staging of gastric cancer and the influence of water-filling method on the accuracy of the preoperative TN staging. Methods：The retrospective analysis was conducted to compare the CT diagnosis and pathological data of 120 gastric cancer patients（water-drinking group：60 cases；no water-drinking group：60 cases）. Results：In the water-drinking group，there was high consistency between CT diagnosis of T staging and pathological data（Kappa=0.714）. In the no water-drinking group，there was medium consistency between CT diagnosis of T staging and pathological data（Kappa=0.506）. The overall accuracies in two groups had significant difference（P=0.039）. In the water-drinking group，there was high consistency between CT diagnosis of N staging and pathological data（Kappa=0.640）. In the no water-drinking group，there was medium consistency between CT diagnosis of N staging and pathological data（Kappa=0.510）. The overall accuracies in two groups had no significant difference（P=0.426）. Conclusion：There is a higher clinical value of application with 64-row spiral CT in the preoperative staging of gastric cancer，and drinking water before the CT scanning could increase the accuracy of the preoperative T staging，which has certain guiding significance on the choice of therapeutic regimen for gastric cancer.