Abstract: This paper presents a small-size low-frequency horizontal omni-directional cylinder transducer which is composed of four cylinder-shaped head masses and four retraced piezoelectric ceramic longitudinal stacks sharing with one back mass.The transducer is analyzed and designed by the finite element method,a prototype is also produced..The results show that the diameter of the transducer was 180 mm,the resonance frequency of the transducer was 1.5 kHz,the maximum transmitting voltage response level was 131 dB and the maximum source level was above 188 dB,was horizontal omni-directional.The transducer is capable of generating low frequencies,is small,and is horizontal omni-directional,have good application prospects.