The invention discloses an automatic pit digging device for planting sweet potatoes. The automatic pit digging device comprises wheels, a belt, a motor and wheel carriers. The wheels are connected with wheel axles, belt pulleys are mounted on the wheel axles and are connected with the motor by the belt, the wheel axles are mounted on the wheel carriers, the upper ends of the wheel carriers are connected with a worktable, the motor is mounted on the lower side of the worktable, a control box is mounted on the worktable, a sensor is arranged on a side of the control box, an alarm is mounted above the control box, a cylinder is arranged on a side of the control box and is connected with a mounting plate, and a connecting sleeve is connected with the mounting plate and is connected with a hoe.The automatic pit digging device for planting the sweet potatoes has the advantages that the automatic pit digging device is simple in structure, convenient to operate and high in pit digging efficiency, the distances between pits dug by the automatic pit digging device can be adjusted and are uniform, and the manual labor intensity can be relieved; the sensor and the alarm are arranged on the automatic pit digging device, and accordingly the automatic pit digging device is high in safety performance.