Abstract: The roll cage consists of antiroll circle, pillar, beams, slant supports, deputy steel tube, reinforcement plate and a ear etc. The 3D model is established by software CATIA and the finite element model is finished by software ANSYS. The numerical simulation on the top of the roll cage under vertical load in 9 tons and on the left side of the roll cage under the load in 5 tons in the angle of 45 degree, are completed by using ANSYS. The results show that the top slant steel braces, the strengthen beam and the back slant supports can improve security of the roll cage structure.