Water　(as　hydrogen)　plays　an　important　role　in　geodynamics　of　our　planet,　not　only　because　it　enhances　the　diffusion　and　creep,　but　also　because　it　lowers　the　melting　temperature　of　the　rock/mantle　(i.　e.　,　＇flux　melting＇).　Furthermore,　fluids　significantly　affect　the　geophysical　properties　of　rock　mass　or　the　evolution　of　geological　structures,　even　trigger　geological　disasters.　Water-induced　influence　runs　through　the　whole　dynamic　process　of　the　plate　subduction.　However,　the　deep　slab　dehydration　(at　depth　＞300　km)　is　controversial,　and　the　dynamic　process　of　water　migration　in　the　subduction　zone　and　its　geophysical　implications　are　still　poorly　understood.　Two-dimensional　chemical-thermal-mechanical　coupling　models,　which　used　northeastern　China　as　example,　were　implemented　to　simulate　the　slab　subduction　process,　with　particular　attention　paid　to　the　whole　continuous　dynamics　process　of　the　fluid/water　migration.　The　simulation　and　analysis　results　show　that　the　process　of　water　migration　during　plate　subduction　can　be　divided　into　three　stages　:　ocean　crust　hydration,　shallow　(middle)　slab　dehydration,　and　deep　slab　dehydration.　Furthermore,　the　mechanism　of　water　seepage　channel　formation,　water　seepage　and　hydration　reaction　of　plate　and　mantle　material　was　revealed　in　the　hydration　process　of　ocean　crust;　the　effects　of　shallow　(middle)　slab　dehydration　process　on　the　formation　of　island　arc,　back-arc　basin,　low-velocity　zone　and　the　similar　to　410　km　discontinuity　were　explained;　the　phenomenon　of　deep　slab　dehydration　was　observed　in　the　numerical　simulation,　which　can　explain　the　causes　of　some　inland　volcanoes　as　well　as　mantle　plumes　(magma　plumes)　and　deep-source　earthquakes　in　some　areas.　This　study　demonstrates　the　geophysical　implications　of　water　migration　during　plate　subduction.