The primary aim of this research is to improve the conventional design process, and make it more suitable for therapy transducer. The optimal design for therapy transducer is also in discussion. In this thesis, the TTF formula has been derived by TWSF, and a new design process has been provided. Furthermore, the analysis procedure has been simplified. By using the new process, the TTF at the working frequency will be the maximum. Finally, the new process and the conventional process show the difference in the simulation results. According to the simulation results of the new process, the optimum design parameters have also been provided.