In consideration of shear deformation and shear lag effects, A new warping displacement mode of T beams is chosen to meet the axial self equilibrium condition for corresponding stress, this paper proposes an approach of analyzing the dynamic characteristics of thin walled T beams with wide flanges generally used in engineering. three generalized displacement functions are employed in analyzing dynamic response of the thin walled T beams by calculus of variations, the differential equations and the corresponding natural boundary conditions of the T beams are induced based on the minimum potential principle, and the dynamic characteristics of thin walled T beams are discussed. The calculation examples compare the finite solid element solutions with the analytical solutions, and the analytical solutions in consideration of the axial self equilibrium condition is still more  identical with the finite solid element solutions, the formulas obtained in this study strengthen the theoretical foundation for further research of dynamic characteristics of the structures.