The vibration system with slow-changing parameters is a typical nonlinear system in which the masses, stiffness, damping and exciting force vary slowly with respect to time comparing with an ordinary parameter system. It often occurs in the working and controlled process of some intelligent structures, when vibration and deformation exist at the same time. In this paper, the system with slow-changing stiffness, damping and mass is analyzed, the relationship between the amplitude and the frequency of the system studied, meanwhile, its dynamic characteristic is also described. In addition, on the basis of the asymptotic method, the piecewise linear method is developed.