The invention relates to a mobile siphonic water decanter. The water decanter comprises a hose and a water intake heat part. A sluice valve is arranged nearby the water outlet end of the hose, a float block is arranged bellow a part of hose in a pond, and the water inlet end of the hose is connected with the water intake heat part. The water intake heat part is provided with a hollow cavity, a bent pipe penetrates through the upper portion of the cavity, a float ring is fixedly arranged around the periphery of the lower portion of the cavity, the end, in the cavity, of the bent pipe is opened vertically downward, and the other end, outside the cavity, of the bent pipe is connected with the water inlet end of the hose through a pipe clamp; the end, in the cavity, of the bent pipe is connected with a bottom valve and vertical downward, and the portion, in the cavity, of the bent pipe is provided with an exhaust pipe which an exhaust valve; a pull rope is fastened to the upper end of the cavity. When the mobile siphonic water decanter is used, the liquid supernatant can be discharged in time and cannot become turbid, the hose is avoided from being evacuated, water in the hose is prevented from flowing backwards to a drying pond, and the condition which induces a siphon phenomenon in the hose is avoided from being damaged.