Abstract: The spectral analysis method for a long-span flat roof structure subjected to wind excitation is established by finite element method. And the wind-induced dynamic response and wind load factor of the long-span flat roofs are evaluated using Davenport wind spectrum and the local mean wind pressure coefficients determined in wind tunnel. The influences of roof stiffness, wind velocity and wind direction on wind-induced dynamic response and wind load factor are discussed. The following conclusions are drawn:① The roof response due to turbulent wind forces is dominated by the first mode and the higher mode effects are very small. ② The influences of roof stiffness and wind velocity on wind-induced dynamic response are considerably large, while the influences on wind load factor are slight. ③ In engineering design, it is suggested to use wind load factor, which is defined as the ratio of wind-induced total displacement to static displacement, to calculate the equivalent static wind load of long-span flat roof structures.