The utility model discloses a hydro flashboard sea-route sand blocking dyke, it includes hydro flashboard which are inserted into floor on two side of sea-route through connection of sliding board and sliding route, the gaps between the flashboard are sealed by pouring; concrete beam which are poured at site; protection slope of stone and sand on both side. The said hydro flashboards have side ribbing, its section is T shape structure, ribbing is inserted interleaving into floor in counter direction. Its top has concrete beam which is poured at site. Sand and stone slope protection are at on both sides. The utility model is characterized of strong integrity, deep depth of base on floor, short construction period, low cost and small later maintenance capacity; it is extensively used in construction of sand blocking dyke in sea-route.