Abstract: Abstract: The straw returning and tillage machine with double roller for high stubble in paddy field had several advantages, such as wide working range, crushing earth evenly, good coverage rate, high working efficiency and so on. The rotary knife roller was the main working part of the machine. The interactions between rotary knife roller and soil included shear, friction and extrusion of knife roller for soil, deformation and failure of the soil and so on. In order to study the interaction characteristics, the soil cutting process of the rotary knife roller was analyzed by Finite Element Method (FEM) software ANSYS/LS-DYNA971 according to the operating feature of the rotary knife roller. The power consumption and cutting resistance of the rotary knife roller were measured by simulation, and the variation rules of equivalent stress of the soil was revealed during the soil cutting process of the rotary knife roller. The maximum values of power consumption and cutting resistance were obtained when the rotational speed was 300r/min and the forward speed was 1.1 m/s, and the values were 6.4 kW and 2820.7 N respectively. The value of power consumption acquired by simulation were accorded with derived value by empiric formulas, which showed that the proposed modeling method was practical and reasonable Furthermore, the maximum equivalent stress of the soil appeared at the inner side surface of the cross knife when lateral blade just cut the soil. Finally, the lateral blade had a lateral push effect on soil in the practical field test, and the adjacent lateral blade had an overlapping time of soil cutting, which could make the machine work more smoothly. The study would provide a theoretical basis for the system parameter's optimal design of the straw returning and tillage machine with double roller for high stubble in a paddy field.