Abstract: In this paper, a simplified model of wire rope isolators is two belieal springs set longitudinally at 180 apart with two rigid retainers. special interest is put on shock excitations in the main direction of the model. The solutions considering pre-loads of maximal stresses and their positions are obtained in the cases of different initial values or amplitudes of shock excitations on the upper or the base rigid retainer, and strength of springs is analysed at last.