A cable tension sensor with bypass excitation structure is proposed based on Villari effect principle of cable. Magnetic circuit is deeply analyzed by calculating magnetic conductance, the cable tension stress can be obtained by measuring inductive voltage in inductive loops. The sensor output may be determined by stress changing, inductive loop denseness, magnetic field and magnetic permeability. In addition,magnetization method, magnetic field intensity and sensor structure sizes are analyzed to determine the parameters of the cable sensors. Finally,a experimental system is developed, and the pulling tension experiment is carried out. The experimental result indicates that sensor sensitivity is up to 1.6 mV/kN, which shows that the magnetic circuit structure and parameter design of proposed sensor are feasible and suitable for cable tension measurement.