本文确定了同相深度可以近似代表土温日变层深度。各层最高、最低温度作成的曲线恰为土温垂直分布曲线族的包络,并分析了曲线族与其包络的切点的性质。从而得出土温日变化层内温度垂直分布的五种类型,基本型为三种“三层式分布”,过渡型为两种“两层式分布”。并评论了对耕层土温垂直分布分型的不适当描述。 This paper confirms that the in-phase depth can approximately represent the depth of soil temperature day layer. The curves of the highest and lowest temperature of each layer are just the envelope of the vertical distribution of soil temperature, and the properties of the tangent point of the curve family and its envelope are analyzed. Five types of vertical distribution of temperature in diurnal variation layer of soil temperature are obtained. There are three types of “three-layer distribution” in the basic type and two “two-layer distributions” in the transitional type. And comments on the inappropriate description of the vertical distribution of topsoil temperature on topsoil.