Abstract: Cosmic-ray neutron method characterized by convenience, preciseness and pollution-free, is one of the most advanced methods to quantify soil moisture at the plot scale. It is able to monitor soil moisture fluctuations in an area of a circle of 300 m in radius. So far, the Hydroinnova, LLC of Albuquerque in US is the only company which is carrying on the research and manufacture of cosmic-ray neutron probe. The author introduced theories of cosmic-ray neutron method, as well as the installation and application of cosmic-ray neutron probe at the suburb of Beijing. In addition, relative factors, which might affect the measurement accuracy of the method, were analyzed. Experimental results showed that: the RMSE and R2 of the soil moisture that derived respectively from cosmic-ray neutron method and oven-drying are 0.011 kg/kg and 0.71, however, before the correction of pressure and atmospheric water vapor, the numbers are 0.022 kg/kg and 0.313. It was demonstrated that cosmic-ray neutron method could sense the fluctuation of the underlying surface soil moisture in the source region accurately and sensitively. In the application, it was necessary to correct the temporal changes of pressure an atmospheric water vapor.