Abstract: It describes the breakdown of the bolt group of the reducer shell and the bolt group of the torque supporting device caused by the foreign body stuck on the roller surface during operation of the roller press, and makes the fault mechanics analysis and comparison, finds out the main failure cause. And it introduces the roller press driving output and input shaft technical requirements and roller press input shaft online welding repair, processing of fault disposal method, summarizes the matters needing attention to avoid the occurrence of failure and ensure the safe and stable operation.