The invention discloses a device for judging the critical balance of the rotation of a bridge, a method for judging the critical balance of the rotation of the bridge, and a method for calculating thestatic friction coefficient of a rotating spherical hinge in the rotation construction of the bridge. The device comprises a beam body, the rotating spherical hinge and a control device. A first jackand a second jack for loading the beam end of the beam body are arranged under the beam end of the beam body. One end, close to the rotating spherical hinge, of the beam body is symmetrically provided with a first adapter plate and a second adapter plate. The first adapter plate and the second adapter plate are respectively connected with a first displacement sensor and a second displacement sensor for measuring displacement. The critical balance state of the rotation of the beam body and the e rotating spherical hinge are searched out during loading, and the measurement of the static friction coefficient of the rotating spherical hinge in the key technology in the rotation construction of the bridge is achieved. The objective of the invention aims at improving the testing efficiency andconstruction safety, and finally achieving the improvement of the rotation construction of the bridge and the decrease of the safety risk of construction.