A new integrated optical three-dimensional (3D) electric field (E-field) sensing system is shown in this paper. In the system, the method of tuning laser’s wavelength is used for controlling the working point of the integrated optical E-field sensor to keep it always in linear working area. The sensing system contains three independent E-field sensors, and the tuning of their working points and the sensing of electric signal are completed by adopting time-division multiplexing (TDM) technique. Then, the theoretical analysis and simulation of the working mechanism of the E-field sensing system are done in this paper. The results show that the bandwidth of electric signal is directly related with the tuning time of working point, and also determines the working rate of the controlling system.