The invention belongs to the technical field of galvanized steel strands, in particular to an ultra-high-strength galvanized steel strand for large-span transmission lines, which includes a central wire, and an inner layer, a middle layer and an outer layer are respectively twisted outside the central wire , the inner layer is right twisted, the middle layer is left twisted, and the outer layer is right twisted; the inner layer is 6 wires, the middle layer is 12 wires, the outer layer is 18 wires, the gap between the inner layer wires is 0, and the gap between the middle layer wires is not Greater than 0.10mm, the gap between the outer wire and the wire is not greater than 0.12mm, the nominal diameter after twisting is 20.16mm; the tensile strength of galvanized steel strand after twisting is ≥1960MPa, the 1% elongation stress is ≥1670MPa, and the elongation rate ≥ 4.0%, torsion ≥ 20 times / 360°, the surface gap of the steel strand is even, no looseness.