The invention discloses a triangular mobile moment arm mechanism. The triangular mobile moment arm mechanism comprises a triangular support frame and a circuit controller. The left triangle bottom edge of one edge of the triangular support frame is provided with a left slipway. The right triangle bottom edge of the other edge of the triangular support frame is provided with a right slipway. A horizontal movement thrust device is arranged between the left slipway and the right slipway. The horizontal movement thrust device consists of a main shaft, a left rolling bearing, a right rolling bearing, a positioning drum-type structure rope roller, a left electric pushing rod and a right electric pushing rod. The main shaft is fixed by the internal-arranged bearings by penetrating through the positioning drum-type structure rope roller. The left and right end parts of the main shaft are correspondingly connected with the left rolling bearing and the right rolling bearing. One end of the left electric pushing rod is connected with the main shaft, and the other end of the left electric pushing rod is connected with the triangular support frame. One end of the right electric pushing rod is connected with the main shaft, and the other end of the right electric pushing rod is connected with the triangular support frame. The triangular mobile moment arm mechanism has the characteristics that a remote control lifting function is achieved, control is convenient, and pouring is stable; and the triangular mobile moment arm mechanism has the advantages that rope control is adopted to avoid deviation, and casting ladle does not swing.