Abstract: A techique to measure the field soil water by using Time Domain Reflectometry(TDR)and its applications are introduced in this paper,including determing soil water content in the root zone and soil water storage for the soil profile;automatic and continuous monitoring soil moisture.The measured soil water can be used to estimate evapot ranspiration in the crop growth season and to evaluate the spatial variability of soil moisture in the field.The three methods of TDR, neutron probe and soil sampling are compared in measuring soil water content.The results showed that the TDR is superior to the other two methods for measuring the field soil water.