Abstract: During under-crossing shield,the real-time risk control of the existing tunnel has been done by using the real-time Georobot automatic deformation monitoring system,of which the component parts,structure and key techniques are expatiated.The results show that all of the risk control values are under their early warning value in the process,and the control effect is good.But some prominent compressive deformation and tensile deformation exist in the structure of the tunnel profile,so some beneficial suggestions for risk control are put forward to ensure the safety.The real-time Georobot automatic deformation monitoring system has several remarkable advantages such as comprehensive deformation information acquisition,high-precision,easy-installation,reusable,etc.