The invention discloses an underwater lotus root digging machine. The underwater lotus root digging machine comprises a float bowl and a seat box, wherein the rear side of the float bowl is provided with a support rod, the two sides of the float bowl are provided with anti-collision rods, the bottom of the float bowl is provided with walking wheels and wheel placement grooves, one sides of the walking wheels are provided with a swinging oar, the upper end of the seat box is provided with a steering wheel, the steering wheel is provided with a control switch, the steering wheel is connected tothe rear end of the float bowl through a connecting rod, the front end of the float bowl is provided with a cutting knife frame, a driving device is arranged between the cutting knife frame and the float bowl, the front end of the outer wall of the bottom of the float bowl is provided with a water outlet transverse pipe, the water outlet transverse pipe is provided with multiple spray heads, the inner wall of the float bowl is provided with a first storage cylinder and a second storage cylinder, an inflator pump is arranged above the float bowl, the other side of the inflator pump is providedwith a water suction port, the water suction port is provided with a filter head, the water suction port is connected with a water suction pump, the middle end of the upper end of the float bowl is provided with a water storage tank, the water storage tank is provided with a vent valve, and the rear end of the float bowl is provided with a power device and a diesel generator in sequence. The underwater lotus root digging machine has the advantages that the operation efficiency of harvesting lotus roots is improved, the use is convenient, and the labor intensity is small.