The invention discloses a live line crossing frame for construction of +/-1100kV line and an erecting method thereof. A rotating arm (7) is arranged at inside of one side tower body (1). The back endof the rotating arm (7) is hinged with a supporting base at inside of the tower body (1) through a cross-shaped hinge (4). The rotating arm (7) can perform vertical rotation around the cross-shaped hinge (4) along the inside surface of the tower body. When the rotating arm (7) vertically rotates to the horizontal position, the rotating arm (7) can perform horizontal rotation around the cross-shaped hinge (4). The front end of a guiding rope (8) is tied to the front end of the rotating arm (7). The guiding rope (7) is connected with different parts of the rotating arm (7) through a plurality ofslip knots. The live line crossing frame is advantages in that because the rotating arm structure is utilized, convenient operation is realized in transferring the guiding rope (8) from one side of the tower body to the other side of the tower body; no tension exists on the guiding rope (8) in a transferring process; long crossing distance is realized; and erecting of the crossing frame on the condition of no power supply stoppage is realized. The live line crossing frame and the erecting method thereof further have advantages of high convenience in erecting the crossing frame, simple structure, high safety, high reliability and low construction cost.