The invention discloses a preparation method for a high-strength cable. The method includes the following steps that: 1) nano semimetal bismuth is bunched so as to be adopted as conductor cores with the core diameter ranging from 60 to 80 nm, each of the conductor cores is coated with an insulated high-strength cable material, so that high-strength insulated wire cores are formed; 2) 3 to 5 wire cores which have been treated in the step (1) are wound around a PV-filled liner core, one-time cabling and stranding are performed, so that a composite wire core can be obtained, a plurality of composite wire cores are arranged side by side, and corresponding force-bearing components are arranged, three-layer co-extrusion cross-linking is performed, two ends of a cross-linked cable are connected with a power source, so that a closed loop can be formed, and the cable is energized for a period of time; and 3) copper tape shielding, cabling armoring and outer sheath sleeving are performed on thecable treated in the step 2). The high-strength cable prepared by the preparation method has moderate softness; after the cable is used repeatedly, transmission speed is not affected; and the aging speed of the cable can be effectively slowed down. The preparation method of the present invention is particularly suitable for communication cables.