In finite element simulation for large strain extrusion machining, changing the width of the margin width, the change rules of effective strain, effective strain rate, effective stress, temperature and cutting force in large strain extrusion machining were analyzed.The results show that effective strain, effective strain rate, effective stress, temperature distribution are all banded. With increase of margin width, the maximum effective strain and the maximum effective strain rate at first increase and then decrease. The maximum effective stress and the maximum temperature have no obvious changes, almost all around 433 MPa and 133 ℃ fluctuation.There is no obvious change in the main cutting force and axial thrust force.