The invention discloses a sirospun yarn and a spinning method thereof. The yarn consists of 25-35 wt% of coffee carbon fiber, 25-35 wt% of bamboo-carbon fiber and 30-40 wt% of cotton fiber, wherein the fibers are spun into the yarn through a siro spinning process. The spinning method sequentially comprises a loose fiber dyeing process, a cotton carding process, a drawing process, a roving process, a fine yarn siro spinning process and a spooling process. The yarn is formed by blending various fibers, the characteristics of each fiber are highlighted by reasonably setting the weight proportion of each fiber, the advantages of various fibers are integrated, the basic performance of the yarn is kept, the propagation of bacteria is restrained, the release of odor ammonia is reduced, and peculiar smell of alcohol, tobacco and the like can also be effectively removed. Compared with the conventional spinning process, the sirospun yarn disclosed by the invention has less hairness than the ordinary ring spun yarn, particularly the long hairness longer than 3mm is well improved, the method has greater advantages in size dyeing, weaving, singeing and other processes, and the woven fabric has a good wear-resisting property, a good anti-pilling performance and better surface handfeel and softness.