The invention relates to a hydroelectric power generating technology which can convert hydraulic energy of arbitrary water conditions into mechanical energy without carrying out damming, closure and impounding to increase the water level and the flow rate. The hydroelectric power generating boat comprises a rack (3), a driving shaft (1) on the middle line and a plurality of hinge fans (9), wherein the rack (3) is supported on a pair of floating bodies (4), and the hinge fans (9) swing around a hinge shaft (8) on spokes. The hinge fans (9) rotating to the force bearing side are propelled by water flows to be attached to blocking irons (13) to push the driving shaft (1) to rotate, and the hinge fans (9) rotating to the non-force-bearing side are unfolded by back flows and parallel to the flow direction and lose counter-acting force, so that the hinge fans (9) rotate in the state that the force bearing side bears force, and the other side is free of resistance all the time. Meanwhile, a flow guiding plate (11) which is obliquely arranged on a non-force-bearing side upstream head and a force bearing side downstream head and flow guiding rings (12) between the driving shaft (1) and the hinge fans (9) collect flows together and change the direction of the force bearing side, the force bearing side angle is enlarged, and flow dividing without power is obstructed. Contained materials of cavities (15) are increased and decreased by means of two-way water lifting devices (6) to balance a boat body and adjust the depth.