Abstract: Objective To analyze the risk factors of vascular invasion in patients with stage T1 a-T1 b gastric cancer and their prognosis, and to provide reference for the clinical treatment of patients with gastric cancer. Methods A total of 80 patients with stage T1 a-T1 b gastric cancer faced the inclusion criteria in the Affiliated Hospital of Hangzhou Normal University from March 2013 to June 2015 were selected and divided into the vascular invasion group (24 cases) and the vascular non-invasion group (56 cases) according to whether the vessels were infiltrated. The clinicopathologic features were compared between the two groups. Cox multivariate analysis was used to analyze the risk factors of vascular invasion. The 3-year cumulative survival rate was compared between the two groups. Results When compared with the vascular non-invasion group, the patients in the vascular invasion group were with higher lymph node metastasis rate (P<0.05), lower proportion of ulcer type in gross classification of tumors (P<0.05), higher ratio of low differentiation (P<0.05), and higher proportion of T1 b stage in the depth of tumor invasion (P<0.05), the difference was statistical significant. There were no significant differences in the cancerous node and tumor diameter between the two groups (P>0.05). Cox multivariate analysis showed that lymph node metastasis and depth of tumor invasion were independent risk factors for vascular invasion in patients with gastric cancer (P<0.05). The 3 years cumulative survival rate of the vascular invasion group was significantly lower than that of the non-invasion group (P<0.05). Conclusion Lymph node metastasis and depth of tumor invasion are independent risk factors for vascular invasion in patients with T1 a-T1 b gastric cancer. The prognosis of stage T1 a-T1 b gastric cancer patients with vascular invasion is not good.