Abstract: One upper pressure roller was fractured,in the course of fatigue test at four-point bending loading for original weld with plate specimen of 10CrNi4MoV steel. That why the pressure roller fractured were analyzed from different aspects of material,load condition,fracture appearance and the results manifested that load condition of the pressure roller was different from the designed initially,further stress concentration was caused in weak part of the pressure roller which made original fatigue crack initiate;simultaneously,the pressure roller material was very sensitive to imperfection which directly resulted in pressure roller fracture. Finally,some useful measures were proposed to redesign the pressure roller.