Abstract: A shrouded blade is investigated in this paper. Using Donnell’s nonlinear shallow-shell theory, the nonlinear equation of vibration is obtained, in which the geometric nonlinearity, damping, shroud contact normal load and friction between shrouds are taken into account. Discretized by a Galerkin method, the nonlinear mode equations are studied by using numerical and analytical methods, then nonlinear frequency-response curves are obtained. The stability of periodic solutions of the system is also analyzed. The results show that the periodic changes in the direction of the friction force between shrouds cause the discontinuity of vibration characteristics of the system. In order to describe the inherent vibration characteristic of the system, two frequency-response curves are drawn, which respectively adopts the positive and negative directions of the friction force. With the changes of the direction of a friction force in a period of T/4, the vibration of the system also jumps between these two curves with a period T/4, this effectively suppress the response amplitude of a shrouded blade, and improves its safety.