It is considered for a long time that damping hasn’t obvious effect to structure’s maximal response when it suffered from a short time shock. So shock isolation system is often designed only in stiffness. Using damping or semi-active damping in shock isolation system is being a study hotspot after the appearance of MR/ER damper. But these studies mainly concentrated in these applications which suffered from a long time shock or only cares the maximal relative displacement such as defend of earthquake. But it is few in these applications which suffered from a short time shock, and have strict demand on both shock isolation efficiency and relative displacement amplitude such as equipment of warship. The effect of viscous damping in soft stiffness shock isolation system is studied in this paper. It is indicated that using of damping can improve the shock isolation performance, but as the enhancement of the soft characteristic of stiffness the improve effect of damping in shock isolation performance descends.