Provided is a full-automatic spacing adjustment device for liquid packaging. The full-automatic spacing adjustment device for liquid packaging comprises a rack, a packaging input module, a packaging output module, an alignment device, and a spacing adjustment module. The packaging input module and the packaging output module are fixed on the rack, and each comprises a conveyor, a liquid packaging supporting plate and a packet arriving detection module, wherein the packet arriving detection module is composed of two sensors which are in diagonal arrangement, and are respectively arranged on the upper side and the lower side of the conveyor, the spacing adjustment module comprises drum shafts, a bearing seat, a coupler, motors, motor fixed seats and a motor height fine adjustment module, the motors are arranged on the left and the right side, and are fixed on the rack through the motor fixed seats, bearings are arranged at the two ends of the drum shafts, and the two ends of the drum shafts are connected with the motors through the coupler, spaced drum shafts are driven by the motor on the same side, and the bearings are fixed on the rack through the bearings. The full-automatic spacing adjustment device for liquid packaging is good in spacing adjustment effect, adjustment distances meet the requirement of an exiting production line speed, and packet abrasion is reduced to the greatest degree in the process of adjustment.