Abstract: Metabolic substance exchange between blood and tissue occurs mainly in microcirculation, which can locally regulate blood pressure and blood flow by changing their diameters.Vascular endothelium plays an important role in the vasomotor regulation of small artery.In this paper, a model was adopted to study the endothelial regulation mechanism.Based on the continuum assumption, two layers of diffusion & kinetic processes of key agents in endothelial regulation were modeled, and the nonlinear viscoelastic properties of the wall material were considered in the computation of radial motion of small artery.The stationary distributions of nitric oxide (NO), calcium ion (Ca²⁺) and the contracting actinmyosin complexes (AMC) concentrations in the wall were firstly obtained;then the process of arterial passive dilation and the autoregulation process to the disturbance of blood flow were simulated.Numerical results showed that there was no oscillation of arterial diameter occurred during the passive dilation process.However, when there was a change in blood flow, the whole system transferred from the initial state to a new equilibrium state with slow damped oscillations.The oscillating period was about 60 s.It is supposed that the endothelial oscillation of artery diameter and NO concentration occurring during the dynamic regulating process is caused by the feedback control of shear stress.This oscillation characteristic can provide useful information for the diagnosis of endothelial dysfunction.