Abstract: A numerical simulation for bending-twisting coupling deformation of unsymmetrical and unbalanced composite laminates under bending load was conducted. The parameters such as laminate width and thickness were also studied. Based on the simulation results, a flexible support device for the four-point-bending test was developed. The flexible four-point-bending tests for unsymmetrical and unbalanced composite laminates were conducted. The test results show that the developed flexible four-point-bending support device does not constrain the twisting deformation of laminates while applying bending load to it. The flexible four-point-bending support device is capable of measuring bending-twisting coupling coefficient of unsymmetrical and unbalanced composite laminates.