In view of the current poor adaptability of soil dielectric calculation model, a bilinear dielectric calculation model was constructed based on bilinear theory. In order to explore the adaptability of the bilinear dielectric calculation model to soil dielectric measurement, seven different texture soils were selected for 0cm3/cm3, 5cm3/cm3, 10cm3/cm3, 15cm3/cm3, 20cm3/cm3, 25cm3/cm3 and 30cm3/cm3volumetric moisture content, dielectric spectrum measurement at different water contents in the frequency range from 1MHz to 3GHz. Through dielectric spectroscopy, the dielectric spectrum of the model can well reflect the dielectric properties of mixed media under different soil water contents; the ideal frequency point of soil moisture content dielectric measurement was 1.50288GHz. At the ideal frequency point, two empirical formulas for frequency domain measurement of soil moisture content were constructed based on the real part of complex permittivity and apparent dielectric constant. Through the analysis of experimental data, the calculated value of real moisture measurement formula of soil moisture content was compared with the measured value of the moisture content of the drying method. The R2 was 0.9126, RMSE was 0.0294cm3/cm3, and RPD was 3343. The soil water content was compared with the measured value of the dielectric measurement formula and the dry water content measurement. The R2 was 0.8907, which was better than that of the other three classic formulas (Topp formula, Roth formula and Malicki formula). The bilinear dielectric calculation model had a good adaptability to the calculation of soil dielectric constant. The frequency domain measurement formula of soil moisture content based on the model had high measurement accuracy for soil water content.