Abstract: During the live working on transmission lines, it is necessary to accurately measure the key distances between the cross arm and the wire, as well as the key distances between the wire and its adjacent-phase wire, in order to better determine the safety distances and select appropriate working methods. The traditional measurement methods present shortages such as complex operation, low accuracy and poor adaptability, while Laser 3D scanning technology breaks through the traditional point-to-point measurement mode and is available to achieve measurement results that are difficult of traditional measurement methods to reach, providing solid data support for the development of maintenance plans and material preparation.