The element contact model of three dimensional spherical element DEM ( discrete element method) is built, which simplifies the interaction between two contacted spheres in space to be four spring dampers and three sliding graters. 建立了球体元三维离散单元法的单元接触模型。该模型把两个球体空间接触时的相互作用简化为四个弹簧阻尼器和三个滑动摩擦器。