Abstract: The use of sensor network to achieve soil moisture real-time detection can provide the decision-making basis for precision agriculture. In this paper, a wireless sensor networks system was designed and developed to collect information of field such as soil moisture¡¢light intensity¡¢voltage and temperature of sensor node, which can direct fertilization and irrigation. For the improved communication protocol stack and dormant/synchronization algorithm have been developed for sensor node, the system can run ceaselessly for over a year with four AA batteries as power supply. Collected data is sent to the server by sink node. Apparently deviant data caused by communication faults or sensor temperature drifts can be dealt with by filter. Statistical analysis would be carried out upon collected data to realize the relationship between characters of the field. Finally, this system has been deployed to Beijing and Xinjiang. According to analysis of collected data, the relationship among characters of corn field and cotton field was obtained, and some issues on optimizing efficiency of irrigation were provided.