<p>Propylene-based random copolymers (PPR) are promising recyclable candidates for high-voltage direct current (HVDC) cable insulation due to their excellent thermal and electrical properties. In this study, three PPR samples with varying ethylene contents and molecular weights were synthesized via Ziegler-Natta catalysis to investigate the influence of molecular architecture on dielectric performance. Characterization results indicate that the concurrent increase in ethylene comonomer content and molecular weight significantly disrupts chain regularity, inhibiting spherulite growth and inducing the formation of the γ-crystal phase. Electrical measurements demonstrate that the copolymer with the highest ethylene content (5.57&#xa0;mol%) and weight-average molecular weight (61.3 × 10⁴g/mol) exhibits superior DC breakdown strength and suppressed space charge accumulation. This enhanced performance is attributed to a combined mechanism: the ethylene-induced structural disorder and lattice defects create deep traps that capture charge carriers, while the high molecular weight reinforces the molecular network through intensified chain entanglements, collectively hindering charge migration. These findings elucidate the critical structure-property relationships in PPR, suggesting that the aggregate effect of comonomer incorporation and molecular weight is vital for optimizing thermoplastic materials for next-generation HVDC cables. This approach enables an optimal combination of electrical insulation properties essential for next-generation, environmentally sustainabley HVDC cable insulation.</p>