In this paper, the effects of thickness and flexibility of confining medium on laser shock strengthening and laser shock forming have been successfully investigated with different experimental method, and the relationship between the rigidity of confining medium and laser-induced shock wave was demonstrated. The experimental results revealed that an appropriate overlay thickness can not only use laser energy effectively but also provide optimal peak pressure of shock waves. It was also apparent from the experimental results that an appropriate overlay rigidity can increase peak pressure of laser-induced shock wave more effectively than flexible overlay, and attain the better effects of laser shock processing (LSP).