Ⅲ type flextensional transducer is a research key in the field of underwater acoustics, with the features of low frequency, broadband, small size and high power. Based on the finite element theory and the finite element software ANSYS, 2.4 kHz Ⅲ type transducer model is established and analyzed. Basic figures of the transducer such as modes in air or water, and the admittance curve of the data are obtained. According to the results and analysis, prototype is made and tested using reasonable structural form and assembly process. Test results basically accord with the theoretical analysis, achieving the expected technical specifications.