Abstract: The MTS software is widely used in the field of fracture and fatigue testing.However,there are still some issues during the data processing for getting the effective J-R curves.Some abnormal phenomena causing the inaccurate testing results such as negative crack extension,crack branching and crack arresting were pointed out,and comparison of fracture toughness parameters obtaining from different blunting line slope defined in different standards was discussed.In the end,some suggestions were given to solve the problems in J-integral test with MTS software.