The configuration principle of lightning protection device is expounded, the lightning protection range of single lightning rod and unequal-height dual lightning rods is analyzed based on the rolling ball method, the cross-sectional calculation formula of the protection range of unequal-height dual lightning rods on the hX height xx’ plane is derived, and the skid-mounted mobile substations of a project is taken as an example, the minimum configuration height of the two kinds of lightning rod is actually analyzed and verified, and the optimal configuration mode and height of the lightning rod suitable for the project are determined through analysis and comparison. It provides a valuable reference for the lightning protection design of related power equipment.