The jumper arrangement in UHV double-circuit transmission lines is more complex, because of the bigger electrical clearance and longer insulator string. By arranging auxiliary tower between two main towers, and rounding the soft jumper from tower inside, jumper exchanged from top to bottom to realize the line transposition in three-pole-composite transposition strain tower. This jumper connecting is simple and clear, which makes the design, construction and operation more convenient, and also makes the overall performance more safety and reliable. The method of separating line-hanging, canceling tower cross arm and optimizing the jumper layout can effectively reduce the size and height, ameliorate the endured force, and improve the structural reliabilities of three-pole-composite strain tower. The weight of three-pole-composite transposition strain tower decreases by 23.4% than that of normal double-circuit transposition tower.