The invention provides a processing method and a device for full-short-fiber composite structure yarns. The processing device comprises a roving feeding coordination device (8), a roving coordination adjusting device (9), a roving coordination maintaining device (10), and a twisting device. The roving feeding coordination device (8) is provided with a first hole (19) for a second short fiber roving fiber strand (2) to pass through, and a second hole (20) for a first short fiber roving fiber strand (1) to pass through. The first hole and the second hole are arranged in an up and down manner. The roving coordination adjusting device (9) is used to adjust left and right relative positions of the first short fiber roving fiber strand and the second short fiber roving fiber strand. The upper surface of the roving coordination maintaining device (10) is provided with a semi-circular groove (33) for the second short fiber roving fiber strand to pass through, and the lower surface is provided with a round concave arc arch groove (34) for the first short fiber roving fiber strand to pass through. The twisting device is used to wind the first short fiber roving fiber strand on the second short fiber roving fiber strand. The processing method and the device for full-short-fiber composite structure yarns are clever in structure and good in practicality.