Abstract: Abstract: During operation of a small rotary tiller, the three-axis working resistances of rotary blade will directly influence the power consumption, moving stationarity of whole machine and wear of blade. Therefore, it is important to measure values of three-axis working resistances and analyze the relative changing rules. But so far, it has been difficult to measure these resistances using a three-dimensional force sensor because the rotary blades are buried in the soil during operation. Discrete element method is a common method to study particle dynamics. Therefore, it would be a feasible solution to discuss the interaction between rotary blade and soil based on discrete element method. Firstly, physical characteristics and mechanical properties of soil from orchard in Guangdong Province were studied by experiments. The soil particles could be regarded as some spheres with a diameter of 1.25 mm. Secondly, a 3D model of rotary blade was reconstructed by reverse engineering. Comparing the side-edge curve of blade in model with Archimedes line, it showed that the 3D model had higher precision. Thirdly, through analyzing the bonding state of soil particles, the formula of computing bonding radius was presented. Lastly, the simulation model to study three-axis resistances of rotary blade was established by EDEM2.6 software, with size of 300 mm×300 mm×600 mm, and particle number of 150 000. Experimental results in the soil bin showed that the practical measured values of torque had the same changing tendency as the simulated results, and the maximum relative error was only 10%. The changing rule of rotation shaft torque was that the value increased to a maximum from 0, then decreased to a minimal value gradually, and then increased to a high value fast, finally decreased again, which agreed with the actual working conditions of blades. Simulation for resistances of single rotary blade indicated that the horizontal resistance acted in the same direction to forward speed, the lateral resistance acted in the direction from inner face of blade to back, but the vertical resistance acted in the direction of down, and then up. The maximum values of horizontal resistance and lateral resistance both occurred at the maximum plowing depth, while maximal value of vertical resistance appeared when the blade turned about 30°. Comparing values of horizontal and vertical resistances with theoretical results and experimental results, it was found that they were the same change law with rotation angle of cutter shaft; meanwhile, the simulation values were more coincident with the experimental values. Finally, single factor simulation tests showed that the maximums of three-axis resistances increased with the increase of the rotation speed, when rotational speed was more than 250 r/min, the increase speed was faster. Maximums of lateral and vertical resistance slowly increased with the increase of forward speed, but maximum of horizontal resistance was in decline. Tilling depth had significant effect on three-axis resistances, so the greater the tilling depth, the bigger the maximums of three-axis resistances, and the power consumption would also increase sharply. This study can provide the reference for saving energy, improving stationarity of rotary tiller and reducing blade wear, and also can prove the feasibility of using discrete element method to analyze three-axis resistances of rotary blade.