We present in this paper our development of a cyber physical sensing platform for monitoring the structural tension of large bridge cables using MEMS vibration sensors and proprietary wireless technology. In order to implement the online tension analysis of the bridge cables, we developed an improved technology for the general identification of cable tension using the Gauss-Newton method to determine the eigenfrequency order and bending stiffness. The improved identification method was applied to vertical suspender cables, i.e., more commonly known as "hangers", of the south section of the Huangpu Bridge. The result shows that the proposed method can effectively estimate the cable tension of the bridge's cables of different lengths.