The utility model discloses a balance weight adjusting device of oil pumping unit belongs to oil field oil recovery apparatus field. The device includes: crank, slider, kicking block, gear pole, locating part. The inside axial of following of articulate is provided with the spout, is equipped with the rack on the roof. Axial displacement is followed to the slider in the spout, the kicking block setting is at the slider top to the adjustment piece of treating that makes the kicking block and set up on the crank offsets. The gear pole includes: gear, circle shaft part, the spanner side's sectionconnected in order, the locating part fastening is passed through on the kicking block to wheel and rack meshing, circle shaft part. The utility model discloses a spanner transmitting gear pole can realize that the cost is lower to the removal of balancing piece, and the material resources of using manpower sparingly are operated safe and simplely to can adjust to optional position on the crank with the balancing piece, improve the work efficiency of adjustment piece.