Abstract: The microstructure can obviously change the strength, toughness and free energy of steel. The principal materials of soil-engaging components of terrain machinery are ferrous metals,so studying effects of microstructure of steel on soil adhesion characteristics has practical significance in aspects such as choosing optimum microstructure,scheming out strengthening processes and developing the technique of reducing adhesion.The dynamic process of the soil adhesion system is analyzed in this paper, and the redistribution of soil particles and water content in the dynamic adhesive process between the moisture adhesive soil and the surface of the metal is described. The practical interface water content in the adhesive system,the constitution of soil surface layer and the microstructure of the metal surface are considered to be main factors affecting the adhesive force. By means of regression design method, soil adhesion characteristics of specimens with different microstructure are studied under different soil water content, loading force and length of time to keep load conditions. The results show that there do exist effects of microstructure of steel on soil adhesion characteristics. The adhesion values for low or high temperature tempered martensite are lower, but for that tempered in the intermediate temperature range is higher.In the present paper, a concept of effective Aispersity is put foreword, then the test results are reasonably explained with alterations of free energy and effective dispersity.