Clinching is a mechanical joint for fastening sheet metal components, and it is widely used in automotive industry. In this paper, the application of mechanical clinching to a built-up aluminum beam is studied. At first, tensile-shear tests and fatigue tests are carried out on clinched joints of 6063-T5 aluminum alloy sheet to investigate the tensile-shear strength and fatigue strength. Then, based on the joint strength results of clinched joint, the joint pitch of the built-up beam is designed under the specified bending load. Lastly, static bending test and cyclic bending test are carried out on the built-up beam to investigate the deformation behavior and the flexural rigidity. It is found that load-deflection relation and load-bending stress relation of the built-up beam are equal to those of one type beam calculated using Euler-Bernoulli beam theory. The built-up beam is proved to have the same flexural rigidity as that of one type beam. Cyclic bending test results show that cyclic loading gives no influence to clinched joints and the flexural rigidity of the built-up beam. All results demonstrate that mechanical clinching is an effective connection method in a built-up beam.