The invention relates to a digital underwater acoustic transducer unit. Two end faces of an outer wall are provided with a sealing film each; each piston radiation surface is fixed to an inner side surface of the corresponding sealing film; the piston radiation surfaces are fixed to the outer wall via elastic members; the two piston radiation surfaces are connected and fixed via a connection rod;a permanent magnet is fixed to the inner side surface of each piston radiation surface; the surfaces, in contact with the piston radiation surfaces, of the permanent magnets have the same polarity; aniron core is provided with a through hole in the middle; the connection rod penetrates the through hole; a coil is wound around the outer side surface of the iron core; an electromagnet is fixed to the outer wall via a fixing connector; end faces of the iron core are corresponding to the positions of the permanent magnets; the transducer unit is filled with oil liquid. The invention also providesa digital low frequency broadband underwater acoustic transducer array and device and a control method. The digital underwater acoustic transducer unit, array and device have the advantages of smallsize, low weight and low power consumption and can realize underwater low frequency large power radiation.