Abstract： Objective To explore the CT criteria for evaluating lymph node (LN) metastasis and preoperative N-staging of gastric cancer through the comparison of CT signs and surgical pathology. Methods Eighty-nine patients with gastric cancer underwent CT examinations before radical resections. A soft-reading method on PACS workstation was employed to evaluate the detection of LNs. The size and number of LNs were registered, and the accumulated size of LNs was calculated in every case. Tile pathological N-staging (pN0-3) was considered on the basis of pathological examination of excised specimens according to UICC TNM-staging system (6th edition, 2002). The relationships between LN metastases and CT findings were analyzed by SPSS using t test and one-way ANOVA analysis. Results The distribution of maximal size, CT detection number and accumulated size were significantly different among different pN stages (P<0.01). All these 3 indicators were significantly different between LN metastasis group and non-metastasis group (P<0.01). There was no significant difference of maximal size among different pN stages in positive metastasis LNs (P>0.05), while significant difference could be found in CT detection number between pN1 and pN3(P<0.01), pNm2 and pN3(P<0.01), and in accumulated size between pN1 and pN3 (P<0.01), pN1 and pN2(P<0.01). Conclusions The involvement of LNs in gastric cancer and pN staging are associated with size, number, and accumulated size of CT detection. CT detection number is more valuable in the evaluation of N staging than LNs size. CT detection number combined with accumulated size of LNs can provide meaningful information for preoperative N-staging.