The invention discloses a conducting rod assembly fixture which comprises three supporting frames evenly distributed on one circle, wherein every two adjacent supporting frames are detachably connected to form an annular framework, the end, located outside the annular framework, of each supporting frame is provided with an idler wheel used for being in contact with the inner wall of a pipe to be installed, the end, located inside the annular framework, of each supporting frame is provided with a support plate used for being in contact with a conducting rod at the center of the pipe to be installed and positioning the conducting rod, and every two adjacent supporting frames are detachably connected in a distance adjustable mode through spiral adjusting mechanisms. The assembly fixture is simple in structure, detachable and convenient to carry. Meanwhile, due to the fact that the distance between every two supporting frames is adjustable, the assembly fixture is applicable to assembly of conducting rods of pipes in different diameters to be installed.