分析了经典摩擦理论中关于摩擦系数的问题，利用弹塑性力学建立摩擦微元体，并给出3 个假设: ( 1) 摩擦力与真实接触面积成正比，( 2) 摩擦剪应力与正应力( 压力) 无关，( 3) 无磨损．然后提出了基于真实接触面积的摩擦模型，并利用该模型分析了等高粗糙、随机粗糙和极端条件下的摩擦力．结果表明: 该模型与经典摩擦系数方法相比有较大的不同，反映了界面摩擦的起因，可以用来有效分析不同类型的摩擦问题．

In this paper,the existing problems with the frictional coefficient in the classical friction theory are analyzed. In order to solve these problems,a frictional micro volume is established based on the theories of elasticity and plasticity,and three assumptions are thus proposed as follows: ( 1) the friction is proportional to the real contact area; ( 2) the frictional shear stress is independent of the normal stress; and ( 3) there is no abrasion or wear. Then,the friction model is constructed based on the real contact area and is employed to analyze the friction problems with the equal-height roughness and the random roughness as well as under extreme conditions. The results show that the proposed model is significantly different from the classical friction coefficient method; and that it reflects the origin of interfacial friction and can be used to effectively solve different friction problems.