Monitoring the deformations of subway tunnels in soft ground is a principal means for selecting the appropriate excavation and support methods in the design. In this paper, briefly describes the basic deformation monitoring requirements, analyzes the tunnel deformation monitoring accuracy difference between mountain area and urban area, discusses the measurements of deformations at ground surface, measurements of deformations on the ground and measurements in the tunnel, especially gives an example of vertical convergence monitoring, introduces the data processing method and the quality evaluating method based on the measured data. Mainly explores the technique of tunnels’ crown settlement monitoring, convergence monitoring and the Automatic Deformation Monitoring methods. It is put forward that the monitoring job during the construction of subway tunnels can be done with both traditional and modern surveying instruments and the job will be significant to the same kinds of projects.