4%。A time domain reflectometry (TDR) used in soil measurements was developed. Based on the measurement requirements of soil parameters, the TDR prototype was designed and manufactured. The pulse generator of TDR can produce a pulse with 140ps rising-edge. The equivalent sampling precision of the TDR receiver was 8.69ps. TDR control software was also programmed and the flow chart of the program was illustrated. The relative permittivities of sand and soil were measured. The volumetric moisture content and electrical conductivity (EC) of the loam and sandy loam are inversed. The inversed volumetric moisture results are close to the weighting method results. The test error is below 4%.