The invention discloses a square pipe universal installation device. The square pipe universal installation device comprises a hoop part (1), a square pipe fixing part (2), a rivet (3), a structure steel beam (6) and a square pipe (7). The hoop part (1) is fixed onto the structure steel beam (6), and the bottom face of the hoop part (1) is provided with a screw hole. The upper-layer surface of the square pipe fixing part (2) is provided with a screw hole, and two supporting foot surfaces with holes are arranged on the lower portion of the square pipe fixing part (2). The rivet (3) is connected between the upper-layer surface of the square pipe fixing part (2) and the bottom surface of the hoop part (1) through the corresponding screw hole, and the square pipe fixing part (2) can rotate horizontally. The square pipe (7) is connected between the supporting foot surfaces of the square pipe fixing part (2) through a pin (5) and the square pipe (7) can rotate upwards and downwards with the pin (5) as the axis. The square pipe universal installation device realizes adjustable fixation of square pipes in decorating and modeling, improves the flexibility of the square pipes in the decorating process and solves the installation problem that the square pipes deflect at will.