Three　experiments　about　KDP　crystal　were　designed　to　analyze　the　relationship　between　the　thin　surface-layer　growth　mechanism　and　formation　of　solution　inclusions.　It　is　found　that　asymmetrical　hydrodynamics　condition　and　imperfect　crystallographic　shape　can　induce　generation　of　a　thin　surface　layer.　The　morphology　of　the　thin　layer　is　observed　under　microscopy　and　SEM,　revealing　that　the　thin　surface　layer　was　composed　of　many　thinner　layers.　At　the　same　time,　the　growth　mechanism　of　thin　surface　layers　was　also　found　in　the　rapid　growth　of　ADP　crystal.　(c)　2008　Published　by　Elsevier　B.V.