The circumferential stress caused by blood flow in blood vessels is closely related to the structural and functional changes of blood vessels. Measuring the circumferential stress of blood vessel models in vitro is an important issue in biomechanics research. A method for measuring the circumferential stress of blood vessels by using fiber gratings was proposed, and a three-dimensional circular blood vessel model integrating fiber gratings was established by using steel needle mold based on microfluidic technology. The relationship between different flow velocities and stress was studied through simulation. The simulation results show that the stress changes linearly with the flow velocity in the range of 8 mm/s~75 mm/s. The circumferential stress generated by fluid flow was measured by fiber Bragg grating sensor. According to the experiment, the relationship between wavelength change of grating and velocity was obtained. When the flow velocity range varies from 8 mm/s to 75 mm/s, the wavelength change caused by velocity is 0.173 nm. The relationship between stress and wavelength change of grating was obtained by simulation experiment. A microfluidic blood vessel model with fiber Bragg grating sensor was proposed and implemented, which provides a new idea for measuring circumferential stress in vitro when blood flows.