The invention discloses a novel colorful yarn on a low-torque section, a preparation method and a preparation device thereof, and a fabric using the yarn, wherein the colorful yarn on the low-torque section is mainly formed by mutually wrapping and twisting more than one of basic fiber fringings and colorful fibers, and its twisting coefficient is below 4.6. The novel colorful yarn on the low-torque section is characterized by low residual torque, softness, smooth and bright surface, low hairiness and high yarn-forming strength, without fiber migration; the prepared textile fabric is characterized by moisture absorption and ventilation, the fabric surface is characterized by smoothness, low hairiness, and soft and smooth hand feeling, before being dyed, the fabric has the special and irregular color change effect, after being dyed, the fabric has the more wonderful outward appearance color, enriches hierarchy and three-dimensional sense, and memorable characters; through the preparation device, yarns are produced under different operating modes, thereby supporting a distribution mode of a spinning system and being convenient to expand capacity in a cotton mill.