The invention discloses a full-water lubricated flexible floating cup type axial plunger pump. The pump comprises a fixed body and a rotating body, wherein the fixed body consists of a front end cover, a flow distribution swash plate, a shell and a rear end cover in sequence; the rotating body comprises a main shaft, plungers, floating cups, elastomers, floating cup trays and sliding bearings; therotating body is a working part and driven by the main shaft to rotate, and sucks and discharges liquid and distributes flow in the rotating process; the heads of the plungers are connected with thefloating cups, and the tails of the plungers are fixed on a turntable of the main shaft; each floating cup is connected with the corresponding floating cup tray through the corresponding elastomer toform a seal between the floating cup and the corresponding floating cup tray; the elastomers limit the displacements of the floating cups; the floating cup trays are connected with the main shaft androtate around a spherical joint of the main shaft; and the bottoms of the floating cup trays are provided with flow distribution grooves which form flow distribution pairs with the flow distribution swash plate. According to the full-water lubricated flexible floating cup type axial plunger pump, a novel form that the structure is mirror symmetrical and the plurality of independent floating cups move relative to the swash plate is adopted, so that the structure and working performance of a traditional axial plunger pump are effectively improved.