In the study of steel fiber concrete beams, there are many design parameters that affecting stress-strain state, cracks formation and cracks development, etc. in beams. Changes of these design parameters will affect bearing capacity, displacement and cracks in beams. ANSYS can simulate the work of beams when design parameters be changed. Therefore, in this paper, the authors used ANSYS numerical simulation method to simulate design parameters of beams which be changed, to bearing capacity such as: steel fiber content in concrete, shear steel stirrups spacing at the ends of the beam, number of tensile steel bars, diameter of tensile steel bars, considering the nonlinear element of the materials, etc to consider the cracks formation and cracks development in beams from the beginning of loading to the damaged beams and then build the load and stress relationship, load and vertical displacement relationship in steel fiber concrete beams. Beam simulation results show that changes of these design parameters have affected the bearing capacity, stress-strain state, cracks formation and cracks development of beams, with the beams when increasing the content of steel fibers in concrete, increasing the number of tensile steel bars, increasing the diameter of tensile steel etc., making the beams reduce cracks, increase the bearing capacity, etc. for the beams. Simulation results were also compared with experimental methods. So, the study of these design parameters helps the design of steel fiber concrete beam structures to withstand impact loads and limit cracks in beams.