Abstract: In order to develop a polyolefin (PO) cable material with efficient flame retardancy, excellent mechanical properties and aging resistance, this study synthesized microcapsulated magnesium hydroxide (MH) using the monomer containing blocked phenolic double bonds (AO-HHA) through free radical polymerization. A multifunctional flame retardant (AO@MH) was successfully prepared, and the comprehensive performance of theses PO composite cable materials were systematically investigated. Compared with pure PO cable material, the peak heat release rate and total smoke release of the PO/AO@MH composite material was reduced by 69.5% and 61.2%, respectively. The peak CO and CO₂ release rates decreased by 61.6% and 68.1%, effectively inhibiting the harmful effects of combustion smoke toxicity and fire risk. After 91 days of thermal aging at 135℃, the retention rate of the elongation at break of PO/AO@MH was still 33%, demonstrating excellent long-term anti-aging performance. These results indicate that the multifunctional flame retardant AO@MH has a good synergistic effect on improving the fire safety, mechanical properties and anti-aging performance of the PO composite cable material. This research provides an innovative strategy for designing long-life and low fire-risk high-performance cable materials.