The Ultra-High Voltage compact transmission technology is of great significance to compressing the line width of corridor, upgrading the transmission capacity of unit corridor width and lowering the construction costs on transmission capacity of unit transmission capacity. And the conductor arrangement optimization is of crucial importance to reducing the electromagnetic effects of the Ultra-High Voltage compact transmission line on the environment and upgrading the transmission capacity of the conductor. This paper proposes a method to optimize the conductor arrangement of 1000 kV compact transmission line, which aims at improving the natural power and the natural power of unit cross-sectional area. A multi-objective inequality constrained nonlinear optimization model is established, which considers the engineering practical constraints. On this basis, further considering the surface field strength distribution of the optimized conductor, the method of particle swarm optimization is adopted for improvement. Then comparison and analyses of the conductor surface field strength and the electrical parameters of the transmission line before and after improvement are presented. Finally, simulations have been done with the finite element analysis method, demonstrating the validity of the proposed method.