The change of water content in rock and soil layers is one of the most important factors inducing geological hazards of landslides and debris flows. In the past, the measuring principles, such as the tensiometer method, resistance method, neutron method, capacitance method, gamma—ray method, optical measurement method, TDR method, have been used to measure water content in rock and soil layers. Those methods have some disadvantages such as low accuracy, great personal harm, great influence by weather, expensive electronic parts. The FDR—type automatic monitoring instrument for multi layer water content in rock and soil layers of the landslide body uses the electromagnetic frequency domain reflection (FDR) tubular water content sensor for measurement, and carries out remote water content data acquisition and wireless transmission with the wireless communication acquisition and monitoring instrument. The automatic multi layer water content monitoring instrument for landslide rock and soil layers has the characteristics of compactness, large measurement range, quick response, high sensitivity, high precision , corrosion and moisture resistance, which has promoted the progress on early warning and monitoring technology for geological hazards.