Mar/scratch resistance is crucial for coatings in many applications. Using a Nano-indenter to make controlled damage, scraping the surface of coatings under pre-selected conditions, and using the Scanning Probe Microscope to examine the scraped surface and study the failure mechanism, we can quantitatively measure the mar resistance, identify different responses of the coating to marring, i.e. elastic recovery, plastic deformation, and abrasive wear, and estimate the critical forces for cracking, delamination and chipping. To give a comprehensive evaluation of mar/scratch behavior of a coating in its application, introduction of a quantitative index is very useful. To define such an index, a quantitative evaluation of different damages is a necessary first step. The operation of the testing, as well as the concept of the index and the quantitative evaluation of different damages, will be introduced in the presentation.