Reducing the impulse grounding resistance of transmission towers is an effective measure to improve the lightning surge withstand capability of transmission lines. However, current methods for reducing resistance generally face challenges in balancing technical and economic feasibility, as well as construction difficulty. Adding short conductors to the grounding device combines the advantages of resistance reduction and simplified construction. This paper explores the use of three?dimensional interleaved short conductors to reduce the impulse grounding resistance of transmission towers, and provides the parameter optimization approach for short conductors. Firstly, considering the influence of nonlinear ionization in the soil, the impulse grounding resistance of grounding device with short conductors is calculated by the CDEGS software. Results indicate that the short conductors with three?dimensional interleaved structure exhibit superior resistance reduction effects. Subsequently, taking the resistance reduction rate per unit length and minimum impulse grounding resistance as indicators, the length and spacing arrangements of three?dimensional interleaved short conductors are optimized. Finally, taking a soil resistivity of 1000 Ω? m as an example, the optimal length and spacing of the short conductors are determined to be 1.1 m and 2.8 m, respectively. The addition of the three?dimensional interleaved structure short conductors to the grounding device can reduce the impulse grounding resistance by 16.52%. This paper provides a method guidance for the design of transmission tower grounding device.