Abstract: With the continuous improvement of distributed power generation technology, prefabricated substations are developing towards large capacity, compact, and modular directions, and efficient heat dissipation has become a difficulty in their miniaturization design. In response to the poor heat dissipation of the low-voltage cabinet in prefabricated substations, which cannot support the long-term stable operation of distributed generation dedicated prefabricated substations, a multi physical field coupling method for the low-voltage cabinet in prefabricated substations based on a proxy model is proposed. A three-dimensional simulation model is established based on actual working environment parameters to simulate the ventilation and heat dissipation characteristics of the low-voltage cabinet. By using axisymmetric simplification analysis and Kriging surrogate model, the calculation speed of field distribution is improved to meet the real-time requirements of intelligent operation and maintenance virtual real interaction. The multi physical field coupling distribution of low-voltage cabinets and the influence of different heat dissipation methods on hot spot temperature rise are analyzed, and an optimization scheme for the heat dissipation structure of low-voltage switchgear suitable for prefabricated substations is proposed. Simulation experiments show that the heat dissipation optimization scheme proposed in this paper through the proxy model can reduce the low voltage side temperature rise of existing prefabricated substations by 21.33% and reduce the calculation time to seconds, providing theoretical support for the structural optimization and customized design of prefabricated substations.