Abstract: In case of power frequency short-circuit fault, the operation of fault current limiter will produce short-term strong electromagnetic environment, which will threaten the safe and stable operation of the secondary system. Therefore, a three-dimensional finite element simulation model of fault current limiter is established in this paper. The domain decomposition method is used in the simulation, and then the electromagnetic environment of power frequency short-circuit is calculated by using the joint simulation platform of MATLAB and COMSOL. From the calculation results, compared with the traditional method, the domain decomposition method can meet the requirements of calculation accuracy and improve the efficiency of finite element calculation. In case of power frequency short circuit, the distribution of magnetic field is in x-axially and y-axially symmetrical distribution, and in horizontally "M" distribution. With the decrease of the height, the position of the maximum gradually moves to both sides. A magnetic field protection method with aluminum plate is proposed, and it has good magnetic field protection effect.