Tribological behaviors appearing in plastic working have several specific features which are strongly dependent on the plastic deformation of work materials and the surface roughness configuration. Although the conventional measurements are effective to yield the dependence of friction coefficient on the lubricant and the prescribed roughness in reduction, variation of traction distributions on the contact interface with the change of surface roughness configuration is beyond their description of lubrication behaviors. The intelligent tribosensing system has been developed as an alternative method to make online evaluation on the variation of friction coefficient or traction distribution with reduction. Three dimensional boundary element model was utilized to represent the whole elastic response of a die through which the interfacial tractions can be insitu measured. Our developed system was applied to the ring-type compression testing. Since both compressive displacement and inner ring diameter were also monitored, the surface traction distributions can be directly obtained in time history of reduction. The rigid-plastic finite element analysis of a ring testspecimen in compression was performed to discuss over the effect of plastic deformation of work materials to interfacial friction behaviors.