Governing equations are derived via Hamilton's principle for composite thin-walled H-type open cross-section beams that show a number of non-classical effects such as transverse shear, primary and secondary warping, and anisotropy of constituent materials. The vibration characteristics of composite thin-walled beams with different elastic couplings, such as circumferentially asymmetric stiffness (CAS) and circumferentially uniform stiffness (CUS) configurations are investigated with respect to the bending-transverse shear coupling and the bending-twist coupling resulting from the directional properties of fiber reinforced composite materials. The dynamic responses of anisotropic thin-walled beams to harmonic and exponentially time-dependent loads are also investigated. It was revealed that transverse shear, elastic couplings, and warping effects greatly influence the free vibration and dynamic response characteristics of composite H-type open cross-section beams.