Abstract: The study of WLAN traffic characteristics is not only important for network performance evaluation but also imperative for the proper network design，management and control.This paper employs actual wireless data drawn from well known archives of network traffic traces and analyzes second-order scaling properties of aggregate WLAN by using the wavelet energy spectrum.For a majority of the upstream and downstream traffic，the second-order scaling exponents at small time scales are fairly close to 0.5，indicating that traffic fluctuations at these time scales are nearly uncorrelated.Self-similarity of wireless traffic at large time scales（larger 1 s） is stronger.Furthermore，the results show that aggregate WLAN exhibits obvious burst effect at every time scale than the assembled Poisson traffic.The observations and results have important implications for accurate wireless networking modeling，traffic control，and optimization of wireless resources.