The rigidity of bending machine is directly affected by the deformation under the bending load,and then the bending accuracy of bending machine is determined, also,the determination of bending load is the key problem.By taken a certain type of computer numerical control (CNC) bending machine as the research object,a three dimensional (3D) model was established by using SOLIDWORKS software.The bending process was simulated with DEFORM3D finite element analysis (FEA) software.It was shown by calculation that the slider was not only bearing the vertical load of bending but also the horizontal thrust generated by sheet metal. The simulation calculation of the bending force was carried out in finite element model of bending machine,in the meantime, and the overall deformation law was obtained from the machine.The finite element calculation results were validated through experimental tests carried out on the deformation of bending machine slide.After comparison, the measured values with the experiments are close to the finite element calculation,and a theoretical basis was provided to further improve and optimize the bending machine structure.