Abstract: A joint bearing outer ring placed in the connecting rod mounting hole by interference fit broke. Combined with bearing structure and material properties, the fracture mode and cause of the outer ring were analyzed by field investigation, fracture macro and micro morphology observation, microstructure analysis, hardness test and finite element simulation. The results show that the fracture mode of the joint bearing outer ring was one time overload fracture. Cracks occurred at the mounting notch of the bearing outer ring under the action of applied load. At the same time, due to the low hardness, local materials on the edge notch fell off into the bearing friction pair, causing abrasive wear and swing stuck, and the occurrence of swing stuck made the outer ring gradually slipped out of the mounting hole, as a result, the tendency of one time overload fracture increased and the outer ring fracture was eventually caused.