Aim To study the dynamics of homocysteine (Hcy) and carotid atherosclerosis in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) and the high risk of stroke, and to investigate the clinic application of the combination of Hcy and carotid ultrasound in screening OSAHS in population with the high risk of stroke. MethodsSelect a total of 200 patients who were found to be snoring during night sleep with the screening of stroke. Analyze the diagnostic value of the combination of plasma Hcy and carotid artery ultrasound for OSAHS in patients with high risk of stroke. Results The incidence of OSAHS in this study was 46.50%. There was no significant difference in clinic characteristics between two groups (P>0.05). Plasma Hcy level in OSAHS group was significantly higher than the control groups (P<0.05). According to carotid ultrasound, intima-media thickness (IMT) in OSAHS group was much thicker than the control group (P<0.05). The positive correlation between plasma Hcy and IMT was observed in OSAHS group (r=0.65, P<0.05). The cut-off value of plasma Hcy in OSAHS diagnosis was 24.045 μmol/L, and its area under curve (AUC) was 0.730. The specificity and sensitivity were 68.2% and 66.7%, respectively. 0.824 mm of IMT under carotid ultrasound was the best in OSAHS diagnosis, with AUC of 0.970, the specificity of 90.3% and the sensitivity of 91.6%. The sensitivity of the combination of plasma Hcy and IMT in OSAHS diagnosis was 60.21% and the specificity and false positive rate were 97.20% and 2.89%. Conclusion Plasma Hcy combined with carotid ultrasound could be applied as a screening method of OSAHS in population with high risk of stroke, which has high specificity.