Abstract: Characteristic of wind pressure pulse is one of the most important behaviors of wind pressure fluctuation. Peak surface pressures measured on wind tunnel test models of long span flat roofs are discussed. The peak-over-threshold method is used to investigate the properties of wind pressures pulse events, which include peak duration, energy contribution, number of the peak events, and the distribution of average peak pressure. The results show that there existed strong non-Gaussian roof pressure in the flow separation region and that the amplitude of peak pressure events could reach four times of the average wind pressures. Some conclusions about the characteristics of wind fluctuating pressure are obtained from these results.