To analyze the incidence and risk factors for postoperative venous thromboembolism(VTE) in patients with stage Ⅰa non-small-cell lung cancer(NSCLC), so as to find evidence for further research of prophylactic anticoagulation. A total of 132 patients with stage Ⅰa NSCLC, 42 males and 90 females aged from 26 to 79 years with an average of (57±10) years, were retrospectively included in this study. All of them underwent surgical treatment at the Department of Thoracic Surgery of Beijing Chaoyang Hospital Affiliated with Capital Medical University from January 2017 to October 2020. A lower extremity venous ultrasound was performed before and after the operation. Participants were divided into VTE group (=11) or non-VTE group (=121) according to whether or not VTE occurred after operation. The surgical conditions, test indicators, imaging information, pathology information were compared between the two groups. Logistic regression analysis was performed to test the associations of VET with putative risks factors in which significant differences were observed. The independent risk factors of VET were determined by this way. Postoperative VTE occurred in 11 cases (8.3%), including 10 cases (90.9%) of deep vein thrombosis (DVT) of lower limbs and 1 case (9.1%) of DVT complicated with pulmonary embolism (PE). The mean age of Patients in the VTE group was older than that in non-VTE Group ((65±9) years vs (57±10) years, =0.009). On the fifth day after operation, patients in both groups had significantly higher D-dimer level compared with that before operation (3.18(1.55, 5.15) vs 1.54(1.09, 2.57); 2.66(1.17, 4.65) vs 1.34(0.78, 2.04))(both <0.05). The value of neuron-specific enolase (NSE) and the number of lymph nodes removed during the operation in the VTE group were significantly higher than those in the non-VTE group ((21.54±12.37) vs (14.72±5.75); (19.7±8.2) vs (13.0±7.9)) (both 0.05). The logistic regression analysis showed that the number of lymph nodes removed during the operation was an independent risk factor related to the occurrence of VTE (=1.306, 95%1.000-1.600,<0.05). The incidence of postoperative VTE in patients with stage Ⅰa NSCLC is approximately 8.3%. The number of lymph nodes removed during the operation may be an independent risk factor for postoperative VTE in patients with stage Ⅰa NSCLC.