The invention belongs to the technical field of harvesting devices for underwater plants, and particularly relates to a lotus root digging device. The lotus root digging device comprises a vehicle body, and a water tank and an air pump are arranged on the vehicle body; the lotus root digging device further comprises moving plates, a U-shaped cavity is formed in the vehicle body, a rounded slider is in sliding connection with the inside of the U-shaped cavity, and the U-shaped cavity is divided by the rounded slider into a right cavity body and a left cavity body. The air pump is communicated with the right cavity body, the water tank is communicated with the left cavity body through a water pump, an exhaust hole is formed in the right cavity body, a sliding hole is formed in the U-shaped cavity, and the rounded slider is fixedly connected with a connection rod which is rotationally connected with the moving plates. The connection rod slides in the U-shaped sliding hole, fixing rods arearranged on the moving plates, cleaning balls are rotationally connected with the fixing rods, cleaning protrusions are arranged on the cleaning balls, water channels are formed in the rounded slider, the moving plates, the fixing rods, the cleaning balls and the cleaning protrusions respectively and communicated with each other, and sprayers are communicated with the water channels. By means ofthe lotus root digging device, sludge around lotus roots can be cleaned, the lotus roots naturally float up, lotus root bodies are not damaged, and the lotus root digging device is most used for digging the lotus roots.