A new,simple method has been adopted of measuring the soil thermal inertia in field conditions combined with determining the thermal capacity of the soil in laboratory,by which the relation between the actual value of soil thermal inertia and the content of soil moisture can be calculated.This method is introduced in the present paper and has been applied to different types of soil in North China Plain. The reproducibility,stability and accuracy of the method were examined when the thermal inertia values for different soil (including 4 types of soils and 4 kinds of soil texture) were given.The results showed that the proposed method was applicable.