Abstract: Corrugated-pipe type solid and liquid mixture vibrationisolator (SALiM) is a new type of isolator for vibration isolation of heavyequipment with low frequency. Firstly, this paper establishes the mechanicsmodel of elastic solid elements by introducing plate-shell model. Based ongeometry nonlinearity of corrugated-pipe, the stiffness of the element underouter liquid pressure and inner air pressure can be obtained by theperturbation method. Then the stiffness of isolator is derived and analyzed,and as a result, the stiffness is piecewise nonlinear and determined byparameters of the solid elements and corrugated-pipe container. In addition,the equation of motion of a single degree of freedom system is given, whichconsists of a SALiM vibration isolator and mechanical equipment. Theproperties of the frequency response function of the system are analyzedusing average method which is a classical analytic method for solvingnonlinear differential equations. And it is found that this system withSALiM isolator shows softening stiffness behaviour. The jumping phenomenonclearly occurs under certain condition, and saddle-node bifurcation of theprimary resonance response can adequately illustrate the jumping phenomenon.