Gravel separation and dehydration device

The invention provides a gravel separation and dehydration device. The gravel separation and dehydration device comprises a rack, and a first washing unit, a collecting tank, a grading dehydration screen and a mud collecting hopper which are sequentially arranged along the rack from top to bottom; the first flushing unit comprises a first pipeline and a plurality of first control valves arranged on the first pipeline; a plurality of first flushing nozzles are arranged on the first pipeline in parallel, and the first control valves and the first flushing nozzles are arranged in one-to-one correspondence; the collecting tank is arranged below the first flushing spray head; the grading dewatering screen comprises a first screen body and a second screen body which are arranged up and down, and the included angle between the first screen body and the horizontal plane is 3-5 degrees; the included angle between the second screen body and the horizontal plane ranges from-5 degrees to-3 degrees. The outlet end of the first screen body is communicated with the first chute; the outlet end of the second screen body is communicated with the second chute; the sludge collecting hopper is arranged right below the grading dewatering screen; and a sludge discharge port is formed in the sludge collecting hopper. The device is high in sand and stone separation efficiency and not prone to blockage.