Abstract:Abstract:By the principle of FDR (Frequency Domain Reflectometry), calibration process of observed automatic soil water content observation equipment is discussed. The model of calibration system is proposed to improve equipment calibration precision and calibration efficiency, also, to reduce artificial labor repeatability, due to the problems of difficult recalibration to the present use into automatic soil water content observation equipment, long cycle calibration, too much calibration links, big error of calibration, heavy artificial workloads. Analysis can get from each link’s errors in calibration and the calibration use of equipment observation data.with the process of calibration.