Abstract: To address the blind spots in the current concentric conductor design of medium-voltage cross-linked polyethylene insulated coaxial cables, caused by the strong coupling between structural parameters and the outer diameter of the conductor and the lack of standardized methods, this paper proposes a quantitative structural optimization design system. The method determines the concentric conductor resistivity (ρ_t) based on the lay factor (λ) and single wire resistivity (ρ_s), calculates the theoretical cross-sectional area (S) using the DC resistance (R_t) specified in the GB/T 3956-2008 standard, and derives the analytical solutions for single wire diameter (d) and the number of wires (n) based on the geometric relationship between the number of layers (N), the pre-lay average outer diameter (D), and S. Taking a 240 mm² cable as the research object, the system yields an optimized solution: n=33 wires, d=2.98 mm, λ=1.028. Measured verification shows: the actual conductor cross-sectional area is 236.1 mm², DC resistance is 0.0750 Ω/km, and resistivity is 17.698 Ω·mm²/km. All indicators exceed standard requirements, with resistivity fluctuation limited to only 0.15%. The "electrical-geometric" integrated design model developed in this study clarifies the quantitative correlation of key parameters, effectively resolving the blindness of traditional empirical design. It provides a reliable theoretical basis and technical tool for standardized design and process control of coaxial cable concentric conductors, demonstrating significant engineering application value.