The S-beam of sports utility vehicles (SUV's) plays a key role in their frontal crashworthiness performance. To study the deformation patterns of the S-beam, a finite element model of a production SUV was developed and validated. Both experimental and simulation results show that large downward and inward deformation occurred at the S-beam in frontal crash. In order to control the deformation of the S-beam, two structural improvement methods were proposed. Computational simulation and tests were conducted to study their effectiveness. Results show that both of these improved methods can control the deformation of the S-beam effectively. The second design was then adapted to manufacture two SUV's for frontal and 40% offset frontal crashes. Experiments showed that the new S-beam design resulted in improvement in structural performance in full frontal crash as well as 40% offset crash modes.