Abstract: In the existing fatigue analysis methods, structural material parameters and geometric dimensions are usually considered to be deterministic variables. For real structures, however, the structural parameters are bounded but uncertain. It is unsafe to estimate the fatigue life of a structure according to the nominal values. In this paper, we apply the interval analysis method based on non-probabilistic set theory to estimating the roof fatigue life under fluctuation wind load. Considering the thickness and elastic modulus of large-span roofs under bounded-but-uncertain circumstances, we calculate the dynamic response range of long-span roof structures under fluctuating wind load by the interval finite element method and interval dynamic response analysis method. The time history curve of the interval stress of large-span roofs is obtained through the constitutive equation and stress. The amplitudes of the interval stress are calculated by the rain-flow counting method. Considering the S-N curve of the roof material, we estimate the fatigue life interval of large-span roofs by Miner's law.