The utility model relates to a beam -pumping unit technical field especially relates to beam -pumping unit balancing piece adjusting device. The utility model discloses a type frame and the articulated cooperation of type B frame, through the pneumatic cylinder application of force, a type frame opens with the reverse cooperation of type B frame and reaches the effect of propping up the balancing piece, reaches the purpose of moving balance piece through rotating the roll axis, has reduced intensity of labour, has reduced the potential safety hazard, has shortened the dead time, has reduced manufacturing cost.