A carbon brush/collector ring set will have phenomena such as firing and ablation during operation, which is due to the existence of various abnormal contact modes of the brush/ring during operation, thus changing the carbon brush/collector ring interface state. To analyze the effects of different contact modes on the performance of the brush/ring, in this paper, we construct the contact modes of the air gap (loss of contact leads to the existence of a small gap between the two surfaces), direct contact (contact with abrasive particulate media), and surface porosity contact (contact when there is a large pit on the surface of the collector ring due to manufacturing quality defects and abnormal abrasion), and analyze the effects of the various states on the core parameters such as current conduction, ring surface damage, and carbon brush abrasion, which provide a basis for the active suppression of the damage.