Abstract: The basic structure of ultrasonic vibrators is studied in this paper. Based on wave equation, the formula of displacement and strain in different section are derived, and the frequency equation is given. By CAD the displacement results, the strain values and the length of sections are calculated corresplndingly. In developing the vibrator, author has made important improvement on structure design and assembling technology. The experimental results extremely approach to theoretical values. The vibrator can be used to replace that from abroad completely.