Laser peening is a promising shock processing technology that enhance the surface properties of metals. When a metal sample is irradiated by a high-peak-power laser pulse, the plasma blow-off is obtained on the sample surface. The plasma is usually confined by the plasma confinement layer, which suppresses the rapid expansion of plasma away from the metal surface, so that a shock wave with a pressure of several gigapascals is generated. The effect of laser peening is greatly influenced by the ability of plasma confinement layer to suppress the expansion of plasma. Therefore, it is important to select an appropriate medium for plasma confinement. Water has been the usual confining medium because it is transparent to the laser, ensures contact with surfaces, and cost effective. However, for those metal materials that are sensitive to water, using the solid medium as a plasma confinement layer should also be considered as well. In this study, the effects of employing pliable solid mediums as plasma confinement layer on laser peening were investigate. Since one of the most important issues in use of solid mediums as plasma confinement layer is to suppress or control the laser-induced damage, it is necessary to consider the appropriate process window for laser irradiation.