The invention discloses an automatic digging machine including an outer shell. Four wheels and four hydraulic telescopic poles are rotatably connected with the outer side wall of the outer shell, a motor is fixedly connected with the inner rear wall of the outer shell, and an irregular gear is fixedly connected with a rotating shaft of the motor. The irregular gear is meshed with a spur gear, thespur gear is rotatably connected with the inner rear wall of the outer shell, and a first rotating wheel is fixedly connected with the spur gear in a coaxial mode. The motor drives the irregular gearto rotate and enable a rotating rod to rotate clockwise, and a spade rotates anticlockwise at the same time. When the irregular gear is not meshed with the spur gear, the rotating rod rotates anticlockwise, a limit iron plate is impacted after a weight block falls down, and the spade is inserted into soil. When the irregular gear is meshed with the spur gear again, the spade rotates clockwise, raises the soil and throws the soil away. The time and labor are saved, the labor intensity is reduced and the work efficiency is improved.