Abstract: This article breaks through the limitations of the traditional three-layer anatomical model of blood vessels by proposing the "fibrous sleeve" as the key structural-functional unit. Adopting a "structure → function → pathology → translation" research paradigm, it integrates elastic fibers (EF), collagen fibers (CF), and vascular smooth muscle cells (VSMC) into a functional whole to elucidate their ultrastructure, biomechanical mechanisms, and structural-functional abnormalities under pathological conditions, exploring clinical translation directions. It clarifies the key structural-functional unit responsible for arterial blood pressure formation and regulation, providing a new theoretical basis for the root-cause prevention and treatment of hypertension. With an "elastin core-microfibril shell" as its ultrastructural foundation and relying on radial waviness gradient for mechanical optimization, the fibrous sleeve maintains blood pressure homeostasis through four synergistic mechanisms: entropy-driven elasticity of elastic fibers, stress buffering by collagen fibers, dynamic stiffness regulation by VSMC, and strain compensation via radial waviness gradient. During aging, hypertension, and atherosclerosis, the fibrous sleeve exhibits degradation of elastic fibers, abnormal hyperplasia and cross-linking of collagen, and dysfunction of VSMC, leading to increased vascular stiffness, decreased compliance, elevated systolic blood pressure, and widened pulse pressure. Based on this theory, early identification and prevention of hypertension may be facilitated through serum desmosine detection and imaging-based waviness gradient assessment. Targeted therapies such as elastic fiber repair can be developed, and novel ideas for the biomimetic design of tissue-engineered blood vessels are provided. The fibrous sleeve theory opens a new path for the root-cause prevention and treatment of hypertension and proactive management of cardiovascular health, offering a fresh reference for scientific and clinical research in the cardiovascular field.