The utility model belongs to the technical field of bridge erecting machines. The bridge erecting machine height adjusting device for road and bridge construction comprises a bottom plate, a first connecting block is fixedly connected to the top end of the bottom plate, a hydraulic oil cylinder is fixedly connected to the top end of the bottom plate, a fixed frame is fixedly connected to the otherend of the hydraulic oil cylinder, a movable frame is arranged on one side of the fixed frame, and a clamping block is arranged on the inner side of the movable frame. A hydraulic oil cylinder, a movable frame, a clamping block, an adjusting block and a clamping plate are arranged; when the height of the equipment is adjusted; the movable frame, the fixed frame and the like are used for fixing equipment; and then the fixing frame is jacked up through the hydraulic oil cylinder, the equipment is jacked up, the lower portion of the equipment is in a semi-suspended state, during height adjustment, adjusting blocks can be added, step-by-step height adjustment and height adjustment are completed, bolts are screwed into bolt holes for fixing, the stability and safety of the equipment are guaranteed, and in addition, when the equipment is adjusted to a certain degree through the arrangement, the equipment height is reduced.