The invention discloses a bent piezoelectric-ceramic low-frequency underwater acoustic transducer comprising a front radiation head, a tail mass block, a front curved beam, a rear curved beam, a front piezoelectric crystal pile, a rear piezoelectric crystal pile, a middle opposite-phase piezoelectric crystal pile, a shell and an output cable, wherein the front curved beam, the rear curved beam, the front radiation head and the tail mass block are respectively stuck on two ends of the piezoelectric crystal piles in a certain mode, and thus the piezoelectric crystal piles are in a 'Z'-shaped bending structure of a zigzag rule shape. The shell is combined with a seal ring to realize underwater sealing. The output cable is characterized in that the leads of the piezoelectric crystal piles are connected to an outer driving source by the tail mass block. In the bent piezoelectric-ceramic low-frequency underwater acoustic transducer, the volume space of the transducer is fully utilized, and the sounding power volume of the transducer is increased; and the longitudinal stretching vibration mode of the piezoelectric crystal piles and the bending vibration mode of the curved beams are fully combined to realize the characteristics of low frequency, light weight and small volume of the underwater acoustic transducer to coexist. The bent piezoelectric-ceramic low-frequency underwater acoustic transducer has the advantages of simple structure, low construction cost and wide application, and is convenient to manufacture and convenient to disassemble.