After the running of ten days in a magnetic train of Beijing,the surface of the brake block has very serious pits and grooves,indicating excessive wear.Macro and micro-morphology analysis,chemical composition analysis,white light interference analysis and X ray photoelectron spectroscopy analysis were carried out on the damaged area of the brake block,and the damage characteristics of brake pads of Cu-based powder metallurgy materials were discussed.The causes of damage failure were analyzed,and some suggestions on how to reduce wear were put forward.The results show that the surface damage of the brake block is serious after service,the deep groove can be observed by macroscopic analysis,and the high temperature burn marks are obvious.The main damage mechanisms are electrical wear,abrasive wear,adhesive wear,oxidation wear and fatigue wear.The matrix material loss is serious,and the Cr alloy is obviously fractured.Due to the high hardness of the Cr-alloy,it will cause serious abrasive wear to the brake block after falling off.There are more cracks inside the brake block,these cracks mainly occur at the junction of graphite and matrix,in which the larger graphite edges have deep cracks,which are easy to produce cracks or aggravate the crack propagation.It is suggested to reduce the particle size of graphite appropriately.