The invention discloses an automatic centralizing and tightening device. The device comprises a power unit vertically arranged on the center of a construction platform, driving flanges arranged on power output shafts in the power unit in a sleeving mode, driving shafts installed on the bottom ends of the driving flanges, partition disks and partition rings which are arranged on the lower middle portions of the driving shafts in a loop overlapping mode at intervals, and jam nuts installed on the lower ends on the driving shafts; arc groove sections are symmetrically formed in the outer left and right surfaces of each partition ring, and the central position of each arc groove section is provided with a steel wire passing hole I with a hole centre opposite to the axis centre of the corresponding partition ring; one pair of steel wire passing holes II are formed in each annular surface where the driving shafts are combined with the partition rings in an axial symmetry mode respectively, and the connection direction of each pair of steel wire penetrating holes II in the upper and lower layers overlaps with the connection direction of every two supporting frames arranged symmetrically. The automatic centralizing and tightening device can help each supporting frame ascend with the platform, and meanwhile, achieve internal synchronization and automatic tightening at equal intervals, and has the advantages of being stable in movement, safe, reliable, and high in adjustment precision and efficiency, and saving labor and time.