液体水是一种极性液体，对太赫兹波有很强的吸收。土壤含水量的细微变化，会影响透射太赫兹波的特性。建立了一种基于时域太赫兹透射谱的土壤含水量测量方法。提出了土壤太赫兹参数的概念，给出了土壤含水量的计算公式。利用太赫兹时域频谱系统，对土壤样品进行了大量的测量，初步给出了土壤太赫兹参数的数值。通过对比该方法与称重法得到的含水量，表明其准确可行。

Liquid water is a kind of polar liquid, and has a strong absorption on the terahertz wave. The tiny change of soil moisture has a great influence on the transmitted terahertz wave. Accordingly, a method is proposed to measure the soil moisture based on time domain terahertz transmission spectrum. Soil terahertz parameters concept is proposed and the equations to calculate soil moisture are derived. Abundant results of soil samples are obtained with terahertz time domain spectroscopy, and the preliminary soil terahertz parameter value is given. By comparison with oven drying method, it demonstrates that this method is accurate and available.