The invention discloses a novel high-efficient floater and a power generation device. The novel high-efficient floater comprises an olivary floating body, wherein a cavity structure is formed in the floating body; a water filling nozzle communicating with the cavity structure is formed in the upper surface of the floating body; a plurality of cable guiding holes are formed in the edge position of the upper surface of the floating body; the floating body is connected with the guyed power generation device through a way of penetrating a cable rope through the cable guiding holes; a baffle plate assembly is connected to the bottom part of the floating body, and comprises a horizontal baffle plate and a longitudinal baffle plate arranged perpendicularly; the horizontal baffle plate is arranged right under the olivary floating body, and is fixedly connected with the floating body; the longitudinal baffle plate is arranged between the horizontal baffle plate and the floating body; and a weight keeper is arranged on the horizontal baffle plate. The guyed power generation device comprises a drive assembly, and a double one-way locking mechanism permanent-magnet direct-current generator; and no matter the floater pulls a guy wire or loosens the guy wire, a permanent-magnet direct-current generator rotor always rotates along a set clockwise direction in a plane perpendicular to a paper surface, so that high-efficient power generation is realized.