The invention relates to a continuous preparation device and a method for orientated electrostatic spinning nanofiber yarn. The device comprises a metal round target and a yarn guide rod. The center of the metal round target is connected with one end of an insulating rod, the insulating rod is driven by a motor I to rotate, a metal top end of the front portion of the yarn guide rod is aligned with the center of the metal round target, the yarn guide rod is perpendicular to a bobbin, the bobbin is driven by a motor II to rotate, the metal round target, the insulating rod, the motor I and the yarn guide rod are arranged on the same center straight line, a spinning jet I and a spinning jet II which are symmetrical with each other are arranged on the left side and the right side of the metal round target and the yarn guide rod, the spinning jet I is connected with a high voltage static positive terminal, and the spinning jet II is connected with a high voltage static negative terminal. By means of the continuous preparation device and the method for the orientated electrostatic spinning nanofiber yarn, continuous production of the nanofiber yarn is achieved, the yield of electrostatic spinning is increased, and both the degree of orientation and the yield of the nanofiber yarn are high.