A hybrid fiber optically powered current transformer with the Hall element is studied and developed in this paper. The sensing probe is the zero-flux current transformer which is based on Hall Effect. The main current can be insulated from the measurement circuit by use of Hall current transformer. Due to the broad bandwidth characteristics and the high linearity between the Hall potential and measured magnetic flux density and the high sensitivity of the Hall current transformer, any changes in the excitation current can be accurately detected without distortion. The three-dimensional model of the Hall current transformer is set up by use of ANSYS software in this paper. The magnetic flux density in the opening air-gap is calculated by nonlinear magnetic analysis method of the three-dimensional finite element. Experimental data shows that the calculation method and results are reliable. At the same time, high power laser power supply is adopted to drive the electronic devices in high potential side, and the reliable insulation between the high potential and low potential is achieved by optical fibers. So the accuracy of this measurement system can be ensured.