We aimed to establish an effective model to identify metastatic lung cancer patients at high risk of venous thromboembolism (VTE). Patients diagnosed with stage IV lung cancer from January 2011 to June 2019 were included in the development cohort; those recruited from July 2019 to June 2021 were included in the validation cohort. Univariable and multivariable analyses determined the risk factors for VTE. Then we assessed the value for predicting VTE of the Khorana score and modified Khorana score in these two cohorts; 575 patients were included in the development cohort, and 202 patients in the validation cohort. Adenocarcinoma, D-dimer, and the Khorana score were independent risk factors for VTE. In the development cohort, the area under the receiver operating characteristic curve (AUC) of the Khorana score in patients with newly diagnosed stage IV lung cancer was 0.598 (95% CI, 0.512-0.684). The AUC of the modified Khorana score was 0.747 (95% CI, 0.689-0.805). The difference was statistically significant ( P <.001). The AUC of the modified Khorana score in the validation cohort was 0.763 (95% CI, 0.661-0.865). The modified Khorana score is more able to accurately predict VTE in patients with newly diagnosed stage IV lung cancer than the Khorana score.