Abstract: For the given working frequency,design of a flexural vibrating stepped circular plate according to frequency equation,the base thickness and radius of the stepped plate may undergo a variety of changes.In order to improve the radiated efficiency,the values of radiated resistance of the stepped plates are expected to be greater.As an example,the radiated impendence of a plate with two steps can be derived from using of superposition method in this paper.Furthermore,the relationship between radiated impendence and base thickness has been calculated while the number of steps has been fixd,and the relationship between radiated impendence and the number of steps has been also calculated while the base thickness is fixd.The results show that the greater the base thickness is and the more the number of steps is (it means the circular plate with greater radius),the greater the radiated resistance is,meanwhile,the reactance shows irregular variation pattern.