Abstract: Objective To explore the effectiveness and safety of heparin treatment before operation for preventing venous thrombosis in patients with high-risk lung cancer. Methods A total of 102 patients with high-risk lung cancer who were admitted to Funing People's Hospital from May 2015 to May 2019 were enrolled. They were randomly divided into two groups (n=51): an observation group and a control group. Patients in the observation group were treated with heparin followed by routine treatment. Meanwhile, the control group received routine treatment alone. Both groups were compared for postoperative thrombotic complications and the safety of heparin use was evaluated. Results Compared with the control group, the observation group showed remarkable decreases in the total incidence of thromboembolism as well as postoperative D-dimer (D-D) value (P<0.05). However, no statistical difference was found in the operation time, intraoperative blood loss, and postoperative platelet between the two groups (P>0.05). Conclusions Preoperative prophylactic treatment with heparin can effectively prevent venous thrombosis in patients with high-risk lung cancer.