The traditional method to determine the soil moisture content and dry density, which uses the oven drying combined with the cutting-ring, has the problems of long testing period and sampling disturbance, thus a rapid non-destructive testing method was proposed based on the frequency domain reflectometry (FDR) technology in this study. Firstly, based on the relationships of dielectric constant and bulk electrical conductivity with the soil moisture content and dry density, and by using the fitting relationship of dielectric constant and bulk electrical conductivity, the solving equations for soil moisture content and dry density were derived. After that, both the calibration test and model test that simulated the layered filling construction were conducted to verify the applicability of the proposed method. It is found that the proposed mothed to detect the soil moisture content and dry density is feasible with high accuracy.