The performance of semi-conductive shielding materials (SCSM) for ultra-high voltage cable directly affects the safety and stable operation of power transmission systems. The CB structural characteristic is a key factor determining the properties of SCSM. In this work, two types of CB (H-CB and L-CB) with different structural parameters were selected to prepare SCSM using ethylene-butyl acrylate copolymer (EBA) as the matrix resin. The influence mechanisms of CB structural characteristic on the electrical, mechanical, cross-linking, and rheological properties of SCSM were systematically investigated. The results indicate that H-CB forms a dense and stable conductive network within the matrix due to its highly branched structure, significantly reducing the volume resistivity of the SCSM and exhibiting excellent resistivity temperature stability. However, H-CB also affects the mechanical properties including both tensile strength and elongation at break. Owing to its high structure degree, H-CB forms a more complete conductive network and stronger interfacial bonding in the SCSM, resulting in superior hot set performance. Rheological tests show that the storage modulus, loss modulus, and complex viscosity of H-CB/SCSM are significantly higher than those of L-CB/SCSM. This work elucidates the relationship between the CB structural characteristic and the comprehensive performance of SCSM, providing a theoretical basis and material selection guidance for the innovative design of SCSM in ultra-high voltage cable.