This paper describes the concepts and the applications of the design system which is developed to carry out optimal design for the high-intensity ultrasonic system. The design system consists of an optimizing program based on a simultaneous search plan and data bases in which data sets, vibration analysis programs by the finite element method, and other programs are included. The optimal value satisfied with design specifications is determined by means of the optimizing program. In this paper, the design of a solid horn that is one in several components of the high-intensity ultrasonic system is presented for an example of applications of the design system. The solid horn with a large diameter that has been produced in the rule of trial and error up to now is developed in a short time by the generative approach in the design system. The success in the applications confirms the practicality of the design system.