As the key part of automobile chassis system, friction material, brake pads are viewed from many aspects. Although more and more strict requirements are put out, wear is still one of the most important assessment index for friction materials. It's influenced by many factors, friction performance level, friction stability, material hardness, even including drivers' driving ways and habits.During driving and braking, pads temperature and rotor temperature go up and down for many cycles. When the temperature is high enough, there are kinds of chemical and physical reactions. Friction film forms and then frictioned out. Among the process, there is a friction interface which is crucial.In this paper, relationship between driving distance, friction interface morphology and wear amount was discussed. Based on a low-metallic formulation, fixed the tested pads on dyno, take out the pads for test when the driving distance is 1000km,2000km,3000km,4000km,5000km. By SEM and EDS, how the materials change in the different stage interface were tested. Connected with wear amount, we could find there is important relationship between the friction interface and wear.