Abstract: In order to satisfy the high-reliability requirements for insulation materials of ultra-fine cables used in industrial robots under extreme environments, a systematic formulation scheme for semi-rigid polyvinyl chloride (PVC) insulation materials was explored. To address the deficiencies of traditional materials in terms of wide temperature range adaptability, bending resistance, and cost, a formulation based on high-polymerization-degree PVC was proposed. The low-temperature toughness and electrical properties were optimized by introducing polyolefin elastomer POE 8150, and a three-dimensional network was constructed by adopting trimethylolpropane trimethacrylate (TMPTMA) irradiation cross-linking technology, through which long-term temperature resistance level was elevated to 125 ℃. Through comprehensive performance validation, applicable temperature range of the developed material was extended to −40~125 ℃, the volume resistivity was enhanced to 5.0×10¹⁴ Ω·cm, and a bending life of over 20 million cycles was achieved. While a performance breakthrough was realized by the material, a cost advantage was simultaneously maintained, and a reliable solution was provided for high-safety and long-life ultra-fine robot cables.