To advance wireless structural monitoring systems mature into a reliable substitute to wired structural monitoring systems, efforts should be paid to investigate their in-field performance on real civil structures, especially complex mega structures. This study carries out an investigation into a vibration monitoring wireless sensor network (WSN) for modal identification of a huge cantilever structure. The testbed under study is the New Headquarters of Shenzhen Stock Exchange (NHSSE). One outstanding feature of NHSSE is its huge floating platform, which is a steel truss structure with an overall plan dimension of 98x162 m and a total height of 24 m. It overhangs from the main tower 36 m along the long axis and 22 m along the short axis at a height of 36 m above the ground, making it the largest cantilever structure in the world. Recognizing the uniqueness of this floating platform, the performance of the WSN for ambient vibration measurement of this structure is examined. A preliminary two-point simultaneous acceleration measurement using the WSN is reported in this paper. The preliminary study demonstrates that the WSN is capable of measuring the ambient vibration and identifying the modal properties of a huge cantilever structure.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.