The invention discloses an ultra-fine tailing filling pipe bag vacuum prepressing dewatering system and a dam construction implementation method. The ultra-fine tailing filling pipe bag vacuum prepressing system comprises a geotechnical pipe bag, a movable vacuum prepressing integrated equipment module, a PVC drainage soft belt and a power supply module. The ultra-fine tailing filling pipe bag vacuum prepressing dewatering system can realize the functions of groove hole dialysis, surface fitting, vacuum hood suction, sand filtration and drainage, manual movement, water and gas replacement, liquid level automatic control, automatic drainage, flexible transportation and the like, provides a mechanical, efficient and flexible low-cost solution for existing tailing pond ultra-fine tailing filling pipe bag damming, solves the problems of limited water content reduction, high material cost and lack of dam construction technology encountered by a high-strength pipe bag flocculation high-pressure dehydration method in a targeted mode, and breaks through the technical bottleneck of difficult dehydration of ultra-fine tailing filling pipe bags on the premise of continuously applying the flatgeotechnical pipe bags in China, and provides technical support for further popularization and application of the pipe bag method damming construction technology in the field of tailing engineering.