Abstract: This paper proposes an approach to analyzing the dynamic response of thin-walled I-beam with wide flange generally used in structural engineering. Four independent generalized dynamic displacement functions , , are employed to reflect the displacement variation of thin-walled I-beams( ), and a new warping displacement mode of I-beams is used to meet the axial self-equilibrium condition. The minimum potential principle is applied to establish the governing differential equations and corresponding natural boundary conditions, and closed-form solutions of generalized dynamic displacements are obtained. The dynamic characteristics of I-beams are discussed. Through calculation examples, the analytical solutions of this paper are compared with the finite solid element solutions, and the validity of the proposed approach is verified.