The stress field monitor and rheological analysis have been done during excavation. The field monitoring data are compared with numerical simulation results. The result shows: Rock stress variation is influenced by both spatial effect and time effect; when the distance from monitoring section to tunnel face is less than a tunnel diameter, the surrounding rock stress is mainly affected by spatial effect and changes violently; when the distance is more than a tunnel diameter, the surround rock presents rheological properties and stress changes smoothly and continuously. Analyzing the monitoring data and fitting by Poynting-Thomson three-parameter rheological model, we can get the radial stress variation equation with time and predict the final variation value. The final value and numerical simulation results are in comparative agreement.