In order to study the effect of constraint conditions on the surface integrity of laser shocked thin plate,304 stainless steel sheets with thickness of 1mm was treated by laser shock processing.The differences in surface morphology,microhardness and microstructure of the sheet under the conditions of both ends clamped (BEC) and bottom fully constrained (BFC) were analyzed.The surface residual stress distribution of different thickness plates and the influence mechanism of constraint conditions were studied by numerical simulation and experiment.The results show that the crater depth on the surface of BFC sample is about 14μm,which is far less than that of BEC sample.The difference of the microhardness in the depth direction of the specimen under the two constraint conditions is not obvious.Fine twins are generated near the surface of the two samples,and the high density of deformation twins improves the microhardness of the material.When the thickness of the plate is less than 2mm,the residual stress field under the bottom full constraint condition is significantly better.The reflection of the stress wave is obviously different under the two constraints,and the reflected stress wave affects the residual stress field of the thin plate surface.