Abstract: To address the issue of frequent breakage of signal, auxiliary power, and grounding conductors in electric vehicle charging cables, a specific type of rubber-sheathed cable was investigated. In the paper, causes of conductor breakage were analyzed from perspectives of materials, structure, and manufacturing processes. Results indicated that conductor breakage failure originated from mechanical imbalances caused by multi-factor coupling: inconsistent bending deformation occurred between large and small cross-section conductors, and unreasonable core arrangement led to stress concentration; excessive sheath tightness was caused by continuous rubber vulcanization, which restricted sliding space for the conductors; coupled with weak rigidity and poor resilience of small cross-section conductors, continuous stress accumulation was triggered under long-term cyclic bending, ultimately leading to metal fatigue fracture. Optimization schemes were proposed accordingly: by optimizing core arrangement and grouped design for signal wire units, along with improving abrasion and tensile resistance of insulating and sheathing materials, comprehensive performance of the cable was significantly enhanced. Test results showed that all performance properties of the improved cable could meet standard requirements, with flexing test reaching over 30000 cycles and drag abrasion test exceeding 50000 cycles, without any failures such as conductor breakage or sheath cracking. The study demonstrated that synergistic effect of structural optimization, grouped layout of signal wires, and material enhancement could effectively solve the breakage issue of small cross-section conductors and extend cable service life, providing a theoretical basis and practical reference for the design, manufacture, and subsequent promotion of rubber-sheathed electric vehicle charging cables.