Abstract: The time domain reflectometry (TDR) takes advantage of the large difference of dielectric constants between water and soils. The dielectric constant and conductivity of soils are obtained from the analysis of the electromagnetic wave reflection waveform, and the water content of soils is obtained through empirical conversion. At present, the researches and application of using TDR to test the water content in the field of geotechnical engineering are mostly limited to soil media, and there are few studies on the municipal solid waste (MSW). In this study, a four-pin TDR sensor developed based on the principle of surface reflection method is used to establish an empirical relationship model between the water content of the MSW media and their dielectric constant through indoor calibration experiments. This empirical relationship model takes into account the influences of the porosity of MSW media. The error of the test results between the TDR technology based on the above empirical relationship model and the drying method does not exceed ±5%.