Abstract: The belt conveyor roller shafts of a logistics company often fractured in the operation, which seriously affected the normal operation of the logistics line. Through macroscopic analysis, metallographic examination, SEM fracture analysis, chemical composition analysis and force analysis, the fracture reasons of the roller shaft were analyzed. The results show that the strength and fatigue properties of material of the roller shaft were reduced due to no quenching and tempering treatment. The rough machining marks on the shaft's surface became the source of fatigue cracks. The fillet radius of the roller shaft diameter changing position was too small and caused the stress concentration. The roller shaft was in continuous operation, so fatigue fracture easily happened at the stress concentrated shaft shoulder. Finally, the corresponding improvement measures were put forward.