Abstract: Conductive carbon black (CB) is a key component of semi-conductive shielding materials (SCSM) for high voltage cables. Its dispersion within the matrix resin is a critical issue for the preparation of ultra-smooth high-voltage cable SCSM. In this work, the small molecular and polymeric dispersants were both selected, and the impact of dispersant type and concentration on the performance of the SCSM was systematically explored. The findings indicates that the non-polar long carbon chain structure of polyvinyl alcohol (PVA) exhibits superior dispersive modification effect compared to small molecular dispersant. The PVA-modified SCSM exhibits the lowest volume resistivity, highest tensile strength, and relatively high elongation at break. The SCSM containing 0.5wt% of the polymeric dispersant achieves optimal electrical properties and surface smoothness. The volume resistivity at 23°C and 90°C is as low as 5.1 and 82.0 Ω·cm, respectively, with no protrusions larger than 60 μm on the surface. Through comparative analysis, the CB in the domestically produced SCSM with the optimized dispersant achieves better compatibility with the matrix resin, resulting in a more stable network structure of CB. This significantly enhances its melting point, thermal stability, and thermal elongation properties. The key performance such as volume resistivity, mechanical properties, and surface smoothness are comparable to that of imported one. This work systematically reveals the impact of dispersants on the SCSM from the perspective of improving the dispersion characteristics of CB, which provides a reference for advancing research on the application of domestic SCSM in high-voltage cables systems.