Objective: To investigate the diagnostic efficacy of thromboelastography (TEG) combined with conventional coagulation tests for lower extremity deep vein thrombosis (DVT) following cerebrovascular surgery. Methods: This single-center retrospective cohort study evaluated 187 patients who underwent open cerebrovascular surgery at Nanjing Brain Hospital between January 2024 and February 2026. TEG parameters (R, K, Angle, MA) and conventional coagulation indices (PT, APTT, FIB, D-dimer) were extracted preoperatively and on postoperative day 3. Bilateral lower extremity ultrasonography performed within 7 days postoperatively served as the gold standard for DVT diagnosis. Multivariable logistic regression was utilized to identify independent predictors, and receiver operating characteristic (ROC) curves were analyzed to assess diagnostic performance. Results: The postoperative DVT incidence was 46.5% (87/187). Patients in the DVT group were significantly older (median: 67.0 vs. 60.5 years, p = 0.001) and exhibited a higher prevalence of comorbid hypertension (66.7% vs. 46.0%, p = 0.007). Univariate analysis showed that the postoperative Angle was significantly larger in the DVT group (72.3° vs. 69.4°, p = 0.001), and the D-dimer level was also significantly elevated (812 μg/L vs. 254 μg/L, p < 0.001). Multivariable logistic regression identified age (OR = 1.036, 95% CI: 1.006–1.066), Angle (OR = 1.107, 95% CI: 1.028–1.192), D-dimer (OR = 1.078 per 100 μg/L increase, 95% CI: 1.036–1.120), and hypertension (OR = 2.678, 95% CI: 1.098–4.724) as independent predictors of postoperative DVT. ROC curve analysis indicated that the AUCs for Angle, D-dimer, and the combined model were 0.638, 0.767, and 0.836, respectively. The combined diagnostic model yielded an optimal cut-off value of 0.513, providing excellent specificity (86.0%) and a sensitivity of 70.1%. The addition of the TEG Angle significantly improved risk reclassification (NRI = 0.078, IDI = 0.034). Subgroup analysis revealed that the combined model had even higher diagnostic efficacy in younger patients (≤ 65 years, AUC = 0.867). Sensitivity analysis showed that the core conclusions remained robust after excluding extreme outliers. Conclusion: The combination of TEG and conventional coagulation tests demonstrates substantial value for the early auxiliary diagnosis of DVT following cerebrovascular surgery. Angle, D-dimer, and hypertension are independent associated factors in this population. The combined diagnostic model provides excellent overall discrimination and high specificity, effectively reducing false positives in clinical screening and offering robust evidence for perioperative targeted anticoagulation management.