Tool for measuring installation error of round steel column

The invention discloses a tool for measuring the installation error of a round steel column. The tool consists of a square metal block, three bracket pipes which are the same in pipe diameter and length, and a measurement bracket pipe, wherein four circular holes are respectively formed in the four sides of the square metal block and are vertical to the four sides; each circular hole is internally provided with an internal thread; one end of each bracket pipe is provided with an external thread; the bracket pipes are respectively provided with length scale markers; the bracket pipes are movably connected with the square metal block; one end of the measurement bracket pipe is provided with an external thread; the measurement bracket pipe is movably connected with the square metal block; the measurement bracket pipe is movably connected with a steel rule at the position where the external thread is not arranged; the lengths of the bracket pipes are larger than the radius of the round steel column to be measured; the measurement bracket pipe is longer than the bracket pipes; the center lines of the bracket pipes and the center line of the measurement bracket pipe are positioned in the same horizontal plane; the included angle formed by every two bracket pipes is 90 degrees; the included angle formed by each bracket pipe and the measurement bracket pipe is 90 degrees. The tool is good in visuality, small in accumulated error and safe to operate.