The invention relates to a spinal fracture posterior quantitative distraction reduction external fixation device for spine surgical department. The device comprises two hollow screws, a fixing connecting rod, a fixed sleeve head, a movable sleeve head, a movable pressure rod, a hydraulic balloon and a meter, wherein a plurality of orifices are formed in the head part of each hollow screw; a screw pole passage is formed in the fixed sleeve head, and the inner diameter of the screw hole passage is accordant with the outer diameter of the hollow screws; a hollow passage is formed in the long shaft of the fixed sleeve head, and the pressure rod and the hydraulic balloon are arranged in the hollow passage; the hydraulic balloon is clamped in the hollow passage between the head part of the movable pressure rod and the long shaft of the fixed sleeve head; the hydraulic balloon is externally connected with the meter by virtue of a meter connector. According to the device, multiple complications caused by unreasonable reduction due to individual experience of spine surgical doctors can be avoided, and the spine surgical doctors are assisted to achieve limited and reasonable reduction of spinal fracture.