Objective To investigate the diagnostic value of color Doppler ultrasound of neck vessels combined with head and neck CT angiography (CTA) in detecting carotid artery stenosis among patients with stroke. Methods A total of 104 patients with stroke admitted to the hospital between January 2023 and November 2024 were enrolled. All patients underwent color Doppler ultrasound of neck vessels and head and neck CTA, with digital subtraction angiography (DSA) used as the gold standard. Receiver operating characteristic (ROC) curves were plotted to analyze the diagnostic performance of each modality alone and in combination for detecting carotid artery stenosis in patients with stroke. Results According to the DSA results, among the 104 patients, 7 were normal, while 47, 16, 25, and 9 cases showed mild, moderate, and severe stenosis and occlusion, respectively. Color Doppler ultrasound results showed 6 normal cases, and 45, 20, 23, and 10 cases of mild, moderate, and severe stenosis and occlusion, respectively. Using DSA as the gold standard, the sensitivity, specificity and kappa value for diagnosing carotid artery stenosis were 98.97%, 85.71% and 0.848, respectively. Head and neck CTA results showed 5 normal cases, and 47, 19, 22, and 9 cases of mild, moderate, and severe stenosis and occlusion, respectively. The sensitivity, specificity and kappa value of head and neck CTA for diagnosing carotid artery stenosis were 100.00%, 71.43% and 0.823, respectively. The combined examination results showed that among the 104 patients, there were 7 normal cases, and 46, 18, 24, and 9 cases of mild, moderate, and severe stenosis and occlusion, respectively. The sensitivity, specificity and kappa value of the combined diagnosis were 100.00%, 100.00% and 1.000, respectively. In the ROC analysis, the areas under the curves of color Doppler ultrasound, head and neck CTA, and the combined method were 0.968, 0.934, and 1.000, respectively, with no significant difference among the three ROC curves (Z = 1.017, 0.994, 1.527, respectively, P = 0.309, 0.320, 0.167, respectively). Conclusion Color Doppler ultrasound of neck vessels combined with head and neck CTA shows good consistency with DSA in diagnosing carotid artery stenosis and its severity among patients with stroke. This combined method demonstrates high diagnostic performance, making it worthy of clinical application and promotion.