At present, the multi-core power cable current reconstruction method is limited by the cable specifications or the sensor array and the core need to be placed according to specific rules, which makes it difficult in practical engineering applications. In this paper, a method based on genetic algorithm is proposed to solve the core distribution correlation of three-phase four-core power cable, then the coupling coefficient matrix between the output of each unit of the magnetic sensor array and the current of each core is obtained when the distribution radius of any core and the angle between any core and the sensor array are obtained, which is used to reconstruct the current of each core in the four-core cable. The feasibility of the algorithm is verified by simulation. In order to effectively reduce the error caused by external factors such as interference, a prior solution model is proposed to improve the quality of the solution. Then, the topology of the sensor unit array circuit is designed. The prototype is tested on the experimental platform. The experimental results show that the maximum error of the measured three-phase current is 2. 42% and the maximum phase error is 2. 77° in the case of three-phase balance. In the case of three-phase imbalance, the maximum error of the measured three-phase current is 2. 52% and the maximum phase error is 4. 17°. The experimental results verify the feasibility and effectiveness of the method.