Objective To examine the monocyte to high density lipoprotein ratio (MHR) in patients with acute cerebral infarction, analyze the plaque characteristics of culprit arteries, and explore the correlation between MHR and plaque stability.Methods A total of 147 consecutive patients with acute cerebral infarction who were hospitalized in Neurovascular Center of The First Affiliated Hospital of Naval Medical University (Second Military Medical University) from Jan. 2019 to Jul. 2020 and underwent intracranial high resolution magnetic resonance (HRMR) vessel wall imaging were retrospectively enrolled, with 27 cases in non-plaque group, 72 cases in mono-diseased artery group, and 48 cases in multi-diseased artery group. The intracranial artery stenosis and plaque stability were evaluated by intracranial HMHR vessel wall imaging. The correlation between MHR and plaque enhancement was explored by Spearman correlation analysis. With plaque enhancement grade used for reflecting plaque stability (grade 0 enhancement was stable, and grade 1 and 2 enhancement was unstable), the influencing factors of intracranial arterial plaque stability were evaluated by binary logistic regression analysis. The evaluation value of MHR on plaque stability was analyzed by receiver operating characteristic (ROC) curve, and the optimal cut-off value and corresponding sensitivity and specificity were calculated according to Youden index. The patients with plaques were divided into high MHR group and low MHR group according to the optimal cut-off value of MHR. The data change of plaque enhancement was obtained during 12.00-month (median) follow-up, and Cox regression equation was constructed to explore the role of MHR in predicting the stability of intracranial arterial plaques.Results The MHR was significantly higher in the mono-diseased artery group and multi-diseased artery group than that in the non-plaque group (P＝0.003, P < 0.001), and was significantly higher in the multi-diseased artery group than that in the mono-diseased artery group (P＝0.003). Spearman correlation analysis showed that MHR was positively correlated with the plaque enhancement (r＝0.469, P＝0.001). Binary logistic regression analysis showed that after adjustment for age, hypertension, stenosis degree of culprit artery, vascular remodeling, and plaque burden, MHR was an influencing factor of intracranial arterial plaque stability in patients with acute cerebral infarction (odds ratio＝2.13, 95% confidence interval [CI] 1.45-3.14, P < 0.001). ROC curve analysis showed that the area under curve (AUC) value of MHR in evaluating the stability of intracranial arterial plaques of patients with acute cerebral infarction was 0.821 (95% CI 0.726-0.915, P < 0.001), with an optimal cut-off value of 0.52×10⁹/mmol, a sensitivity of 0.75, and a specificity of 0.80. There were 44 patients in the high MHR (MHR≥0.52×10⁹/mmol) group and 76 patients in the low MHR (MHR < 0.52×10⁹/mmol) group. The plaque enhancement in the high MHR group was significantly higher than that in the low MHR group (P＝0.009). Cox regression analysis showed that low MHR was associated with the stability of culprit artery plaques (hazard ratio＝3.21, 95% CI 1.92-5.36, P < 0.001).Conclusion MHR is correlated with the stability of intracranial arterial plaques of patients with acute cerebral infarction, and it has a predictive value for the plaque stability, and probably is a marker of the stability of intracranial arterial plaques.