Damping is one of the basic dynamic properties of structure in vibration ,it has considerable effects on structural dynamic response. Structure has different damping ratio in different vibration modal because structure damping energy dissipation is from the friction, and the friction energy magnitude is decided by vibration modal. It is unreasonable that all modal damping ratio is constant in current codes. This paper discussed the reasonable damping ratio in low amplitude vibration and strong vibration by the relationship of basic vibration modal and other modals, the Revised Rayleigh damping...