The frequent occurrence of tunnel safety accidents threatens the safety of people's lives and property, and the research on the on-site monitoring and measurement technology of tunnels is very necessary. Practical applications of tunnel on-site monitoring and measurement technology include electronic total station and micro-deformation monitoring radar. Among them, radar interferometry technology is used for deformation monitoring in on-site monitoring and measurement, such as vault settlement. The built millimeter wave radar deformation measuring instrument can complete the vault settlement monitoring of the tunnel on-site monitoring. During the tunnel construction period, it is necessary to make a selection according to the specific engineering objectives, adopt appropriate observation and test methods, obtain new deformation displacement information, and analyze and predict the deformation of the construction.