To study the relation between the surface morphology and the deformation mechanism of the target material under the shock, a flexible loading condition, in laser shock peening (LSP), the surface morphology of 304 austenite stainless steels treated by LSP is investigated using the optical microscope. The surface features observed present the characteristics of plastic deformation in the polycrystalline face centered cubic (FCC) metal. The surface microstructure can directly represent the deformation mechanism of the material under shock wave loading. The experimental results show that the surface morphology of the treated material corresponds to the deformation mechanism, which provides a new experimental method of studying the deformation mechanism in LSP.