The invention discloses an orientation electro-spinning nanometer fiber spinning method and a device thereof. A metal shower nozzle which exerts positive and negative high pressure is adopted to spin two strands of nanometer fibers with opposite charges, an electric field line of a spinning electric field, relative to a common spinning electric field, is straight, stability of spinning is effectively restrained, and the spinning nanometer fibers are straight. Two strands of the fibers surround the yarn tail and form a cone-shaped twisting trigonum on the upper portion of a metal twisting machine, and enable the nanometer fibers to be further oriented and twisted to form yarn through electric field force, tractive force of the yarn and acting force of the metal twisting force. The spinning nanometer fiber yarn is conducted heat shaping through a heat processing device under certain tensile force, degree of orientation of the nanometer fibers along the axial direction of the yarn, breaking force and yarn levelness are further improved, and the yarn after shaped is collected by a winding bobbin. The device can achieve the aim that orientation nanometer fiber yarn can be continuously prepared, is simple in device, convenient to operate, and good in resultant yarn continuity, yarn breaking strength and yarn levelness, and not only can spin pure nanometer fiber yarn, but also can spin nanometer fibers / filament core composite yarn. The orientation nanometer fiber spinning method and the device thereof have important application value in the fields, such as a biomedical field and a sensor field.