The utility model discloses a device for assembling a three-phase box-sharing conducting rods, and the device comprises a support. The support is provided with three supporting grooves which are used for the supporting and positioning of the conducting rods. The positions of the three supporting grooves are respectively corresponding to the installation positions where the conducting rods are located in an installed pipe. Stopping structures, which are used for blocking the conducting rods and preventing the conducting rods from separating from the supporting grooves, are respectively disposed above the notches of the three supporting grooves. The support is provided with three supporting legs which are located in a circular plane perpendicular to the axes of the conducting rods and extend along the axial directions. The outer ends of the three supporting legs are connected with a wheel frame through adjustable connecting mechanisms. The wheel frame is provided with a roller which is used for contacting with the inner wall of the installed pipe. The device is light and exquisite in structure, can be suitable for installed pipes with different diameters, and reduces the cost of application.