The invention discloses a desilting device for a pond. The desilting device comprises a fixed base, a first motor, a rotary shaft, a gear, a rack, a lifting base, a water pump, a connecting tube, a stain absorption tube, a second motor, a connecting rod and a dredge tool bit. The desilting device is delicate in structure, is strong in function, can be firstly used for performing negative-pressure type suction treatment on sludge inside the pond, can realize regulation on lifting height of the device though simple operation, i.e., improves the sludge suction effect; and finally, a dredging device further can be internally arranged according to a practical condition for crushing and breaking aquatic plant inside the sludge. In this way, the desilting device realizes efficient clearing for sludge inside a fish pond.