According to the scheme selection of 220 kV double-circuit transmission lines undercrossing 500 kV transmission lines, this paper analyzed the restricting factors of undercrossing scheme. Some measures were suggested such as changing suspension form of ground wire, arrangement mode of conductors and insulator string type of jumper wires. Finally, this paper designed and optimized the undercrossing tower, and proposed a double-circuit tension tower with olecranon-butterfly type. The engineering practical application proves that this tension tower has a good promotion prospect, and can provide a feasible solution for 220 kV double-circuit transmission lines undercrossing 500 kV transmission lines.