〔Abstract〕 Objective To analyze the application value of magnetic resonance imaging (MRI) combined with carotid artery ultrasound quantitative parameters in the evaluation of the condition and efficacy of elderly patients with acute cerebral infarction (ACI)-induced vascular dementia (VD). Methods A total of 120 elderly patients with acute cerebral infarction who were admitted to Zhuhai Fifth People's Hospital and ZhuJiang Hospital of Southern Medical University from January 2021 to July 2022 were selected, and all underwent MRI combined with carotid ultrasound examination, divided into non-VD group (21 cases) and VD group (99 cases); before treatment, patients in VD group were divided into mild group, moderate group and severe group according to the clinical dementia rating scale, with 32 cases, 41 cases, and 26 cases, respectively. After treatment, the patients in VD group were divided into the effective group (89 cases) and the ineffective group (10 cases) according to the curative effect. The carotid ultrasound parameters [carotid intima-media thickness (IMT), internal carotid artery peak systolic blood flow velocity (PSV), end-diastolic flow velocity (EDV)] and MRI-related parameters [width of ventricle and schisis, white matter apparent diffusion coefficient (ADC)] were compared between groups. Results IMT comparison before treatment: non-VD group < mild group < moderate group < severe group; comparison of PSV and EDV: non-VD group > mild group > moderate group > severe group, the differences between the groups were statistically significant ( P < 0.05); comparison of the width of ventricle and schizophrenia before treatment: non-VD group > mild group > moderate group > severe group; ADC comparison: non-VD group < mild group < moderate group < severe group, the differences were statistically significant (P < 0.05). After treatment, IMT in the effective group was significantly smaller than that in the ineffective group; PSV and EDV were significantly greater than those in the ineffective group (P < 0.05); the width of ventricles, schizophrenia, and schizophrenia in the effective group were significantly larger than those in the ineffective group, and ADC was significantly smaller than that in the ineffective group (P < 0.05). Conclusion MRI combined with carotid ultrasound quantitative parameters can effectively evaluate the disease severity and curative effect of elderly patients with VD caused by ACI, and guide the clinical formulation of early intervention measures.