The converter transformer is an electrical equipment with a symmetrical structure. Due to its symmetry, the ground current should be small when the core is grounded at one point. The research and analysis of grounding currents in the converter transformer can effectively help staff to judge the working state of the converter transformer. Therefore, it is very meaningful to study the calculation problem of the grounding current under the multi-point grounding state. First of all, a homogenization modeling method considering the characteristics material of the core silicon steel sheet is proposed; secondly, on this basis, the finite element simulation model of multi-point grounding of the core of the converter transformer is established and simulated; then a multi-point grounding test was conducted using the shrinkage model of the converter transformer to verify the finite element simulation results; the final consequence show that the homogenization modeling method can effectively calculate the grounding current at multi-grounding.