A pre-assembled substation has the basic functions of electric power automation, compact structure, and easy installation, on the basis of which this study optimizes the internal space structure of the pre-assembled substation and designs an intelligent pre-assembled substation architecture using intelligent control. Then, to ensure the stable operation of the pre-assembled substation in outdoor spaces, photovoltaic power generation is used as an auxiliary power source to enhance the operation and compensation of the pre-assembled substation. This study also optimizes the results of the substation’s box to address the stability and transport issues associated with the outdoor operation of the pre-assembled substation. Finally, the simulation experiment reveals a maximum stress of 0.33s, a value of 66.53 MPa, and a maximum deformation size of 1.15mm. The top is smaller than the bottom, resulting in less stress and deformation. This indicates that the optimized layout of the pre-assembled substation structure in this paper effectively ensures the stability of the internal equipment structure during the transport process. At the same time, the optimized design of the pre-assembled substation in this paper has a phase voltage current and voltage signal ([−2.3, 3.2] kV between), stable voltage, and stable grid operation. Under the optimal compensation parameters, the dynamic reactive power compensation device demonstrates a remarkable compensation effect, further substantiating the impact of optimizing the space structure of the pre-assembled substation in this paper.