In order to achieve the refinement of modern agricultural production requirements, this paper designed a portable soil moisture sensor, it can realize automatically collect and transfer soil information. The system takes the MCU as the core, via wireless transmission technology and uses TCP/IP protocol to send the data of soil to the remote control center and process it. This system overcame the disadvantages of traditional soil moisture sensor such as the low precision and bad real time capability and difficult to carry. The analysis results show that:error of FDR soil moisture sensor measurement is small and data transfer is correct, so it can be able to complete work reliable. The sensor is simple to use, not only suitable for use by technicians in the field, but also has practical significance through the soil moisture monitoring to guide agricultural irrigation.