Abstract: This study proposes a modular substation integration design optimization framework for zero carbon objectives. By establishing standardized prefabricated cabin structures, integrated electrical equipment layouts, and combining intelligent sensing with energy efficiency control systems, the framework enables factory based prefabrication, modular construction, and smart operation of substations. A carbon emission quantification model covering the entire life cycle from "materials construction operation recycling" is developed, with systematic decarbonization strategies proposed for key modular design phases. Additionally, a flexible control architecture supporting high-proportion renewable energy plug and play and active coordination is designed. Simulation and operational data from pilot projects demonstrate that the optimized modular substation solution reduces carbon emissions by approximately 35% during construction, decreases operational losses by over 18%, and improves equipment land utilization by 40%. These findings provide a practical technical solution for the rapid, low carbon deployment of zero-carbon grid infrastructure.