The design of ultrasonic transducer is used to achieve the desired value of terminal vibration amplitude. However, in many practical applications of ultrasonic transducer, the maximum vibration amplitude failed to achieve that value such as ultrasonic machine and bonding. For that matter, the design of ultrasonic transducer used APDL optimization method. In this paper the optimal design of a sandwich ultrasonic transducer is investigated. The design problem is formulated mathematically as a constrained single-objective optimization problem. The maximum vibration amplitude is considered as optimization objective. Design variables involve continuous variables and discrete variables. What is more, the behavior of ultrasonic transducer is modeled using ANSYS based on models of the transfer matrix method. In this paper, the optimized results are analyzed and the vibration amplitude is determined.