There are many objects to be simulated in the secondary circuit of a smart substation, and it has the characteristics of timing and non timing. This leads to the poor three-dimensional visualization. A three-dimensional visualization system of the secondary circuit of a smart substation based on a GIM model is designed. The hardware part of the system focuses on the design of processor, transformer sampling module and transformer sampling module. In the system software part, the spatial data organization and management, intersection calculation between geometric elements, model cutting and fitting are carried out. The timing model is established using the GIM model to complete the design. The experimental results show that the proposed system not only improves the modeling frame rate, visualization efficiency and effect, but also has no defects in the visualization results. It also reduces the number of construction changes, cost and period, and the maximum reduction of the construction cost is close to 0.5. Therefore it shows that the designed system improves the three-dimensional visualization and can meet the requirements of system design. This work is supported by the Science and Technology Project of State Grid Corporation of China (No. 062901-DMSJY).