Background: This study aimed to utilize high-resolution magnetic resonance imaging (MRI) to investigate the characteristics of stable and vulnerable carotid arteriosclerotic plaques, with correlations to histopathological findings. Patients and methods: High-resolution MRI was performed in 817 patients, using three-dimensional magnetic resonance angiography. Plaque composition was evaluated by measuring the areas occupied by calcification, a lipid-rich necrotic core, intraplaque haemorrhage, and fibrous cap rupture. Plaque morphology was analysed by measuring vessel wall area, thickness, and luminal area at the bifurcation of the common carotid artery. Plaque tissues were sampled during carotid endarterectomy and examined using haematoxylin-eosin, Oil Red O, Masson trichrome staining, and immunohistochemical staining for CD68. Results: Patients were divided into stable plaque group (n = 462) and vulnerable plaque group (n = 355), based on intraoperative observations and postoperative histopathological findings. Compared to the stable plaque group, the vulnerable plaque group exhibited increased vessel wall areas and thickness, and decreased mean luminal areas (P < 0.001). The vulnerable plaque group also had a lower collagen content, a higher lipid content, and higher CD68 expression in plaque tissues on histological examinations (P < 0.01). Incidences of lipid-rich necrotic core (38.1 % vs. 34.3 %), intra-plaque haemorrhage (26.9 % vs. 22.8 %), plaque calcification (45.2 % vs. 40.9 %), and fibrous cap rupture (36.0 % vs 39.8 %) in the plaques were concordant with MRI observations and histopathological findings (p > 0.05). Conclusions: Stable and vulnerable carotid plaques had different morphologies and compositions. High-resolution MRI can assess such differences qualitatively and quantitatively in vivo and provide guidance for risk stratification and management.