Abstract: Vibration modes and natural frequencies of overhead bridges hold important characteristics information about the structural health condition of the bridges. Vibration mode and dynamic frequency analyses are the reliable and widely adopted non-destructive assessment techniques for the detection of damage or any form of degradation in bridge structures. Various measurement technologies have been proposed for this application for instance, the wireless MEMS system. However, this technology has technical challenges such as the time synchronization, intermittent connectivity of the sensing modules and multi-path errors. On the other hand, fibre-optic sensors such as fibre Bragg grating (FBG) accelerometers turn out to be a better solution in terms of immunity to electromagnetic interference, low attenuation loss, large area coverage and synchronous multi-point measurement capability. In this work, we will present the results of dynamic frequency analysis for a ~110m long steel cable suspension bridge located in Bukit Gasing Forest Reserve – Taman Rimba Bukit Kerinchi, Lembah Pantai, Kuala Lumpur, Malaysia. Seven FBG based accelerometers have been used for measuring the vibration responses of the bridge based on single-pulse excitation. Taking advantage of the synchronous data from all seven sensors, the mode shapes of the lowest three natural frequencies can be easily identified. The time-varying responses of the mode shapes can be constructed from the data. This information is important and useful for the structural analysis and integrity assessment of the bridges.