The phase and morphological changes of crystalline material during laser internal ablation with and without water on the material surface are studied using molecular dynamics simulations. The atomic image of the material morphology was obtained by recording the velocity and position variation of atoms. Temperature distribution contour of the crystalline material along the ablation process are charted by statistical physics method. Furthermore, density variation and phase variation contour of water are also charted. The results suggest that: First, during the ablation process of crystalline materials, energy transfer occurs between water and crystalline materials. Supercritical water is formed first, which restrains the sputtering of crystalline materials due to phase explosion and puts off the sputtering. Then the physical state of water changes from liquid to gaseous. Second, with water on the surface, the cavity shape is different from that without water, the width of upper part of cavity is decreased. Third, the volume of the cavity is affected by the thickness of the water layer.