Abstract: This article establishes a mathematical geometric model for the design of a 3 000 mm² large section segmented conductor structure. Based on the existing design and manufacturing of large section segmented conductors for high voltage cables, the precise design of the size of the 3 000 mm² segmented conductor structure is completed, and key technologies such as the manufacturing process of large section segmented conductors and direct current resistance detection of conductors are emphasized. The research results indicate that precise process design and strict quality control can significantly improve the stability, roundness, and good conductivity of segmented conductors, The trial conductor has a roundness value less than 0.8 mm, and the DC resistance at 20 °C is about 0.005 8~0.005 9 Ω·km⁻¹, fully meeting the performance requirements of ultra-high voltage cables. At the same time, this study provides design basis and practical guidance for the design and manufacturing of large section segmented conductors for high-voltage cables.