To develop a new type of semiconductive shielding material for high-voltage cables, this study selected highly conductive carbon blacks from four different manufacturers worldwide, produced via distinct methods, to prepare semiconductive composite materials. The research investigated how the dispersion and structure of the carbon black itself influence the electrical conductivity of the composites. The structure of carbon black primary particles and agglomerates was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The graphitization degree, carbon atomic order, and surface purity of carbon black were characterized through experiments including Raman spectroscopy and X-ray diffraction (XRD). The macroscopic conductivity of the shielding material was studied via volume resistivity measurements. Results indicate that a well-structured, highly branched three-dimensional conductive network is crucial for achieving high conductivity and stable electrical performance in shielding materials. Under this premise, carbon black graphitization and purity can further enhance material conductivity. These findings provide reference for domestic development of high-voltage cable shielding materials regarding carbon black structure and properties.