Abstract: Phase current of three-core cable is an important parameter for condition monitoring, which cannot be directly measured non-invasively by traditional ferromagnetic current transformers around the surface of three-core integrated cable. In this paper, six Hall sensors are designed to be clapped around uniformly on the circular surface of cable, whilst the magnetic induction intensity along the cable surface is modeled, the nonlinear equations of the phase current and the magnetic field at measured points are deduced based on Ampere circuital theorem, the differential evolution algorithm is proposed to solve the nonlinear equations of the measured magnetic field and phase current, and the model as well as method are verified by simulation and experiment. The results show that the differential evolution method is better than particle swarm optimization and genetic algorithm in the simulation. Under the simulation condition of symmetric cable core, the magnitude error of the calculated phase ABC current is 0.02, 0.01, 0.01 A, and the phase error is 0.00°, 0.01°, 0.01°, respectively. Under the simulation condition of asymmetric cable core, the magnitude errors of the calculated phase ABC current is 0.48, 0.88, 0.71 A, and the phase error is 0.14°, 0.11°, 0.08°, respectively. The experimental results show that the three-phase current error obtained by differential evolution inversion is minimum, the three-phase current magnitude error is within 4.14 %, and the current phase error is within 0.23 rad. The ratio and phase error of the proposed annular Hall sensor is approximate to the current transformer class 1.0, which can meet field test demand.