To study the influence of extrusion temperature on the mesoscopic morphology and comprehensive properties of high-voltage cable insulation masterbatch, and analyze its mechanism, insulating materials with different mesoscopic micro-morphologies were prepared by controlling the extrusion temperature of the insulating material. Then, combined with the microscopic characterization of the system, comprehensive electrical and mechanical performance testing, and simulation methods, the reasons for the performance differences of insulating materials are revealed and the mechanism is verified and analyzed. The results showed that at an extrusion temperature of 120 ℃, the insulation material could be fully plasticized without excessive melting, and the crystallinity and crystal size of the insulation material reached the optimal values of 42.28% and 15 μm, presenting a dense and uniform crystal configuration. Based on the mutual verification of simulation and experimental results, it can be concluded that a perfect crystal configuration, significantly increased crystal size, and crystallinity can synergistically enhance the comprehensive electrical and mechanical properties of insulation materials, resulting in optimal values of 7.85 × 1017 Ω·cm, 390 kV/mm, 17.1 MPa and 675% for volume resistivity, breakdown performance, tensile strength, and elongation at break, respectively.