By using sirospun process, a spin-twisted yam can be produced directly on the ring-spinning machine. Two rovings are led paralel through the drafting system and then separated by two special condensers and drafted separately. When compared with a single yam with same yam count, sirospun yam is better in hairiness, strength and abrasion resistance. Furthermore, it's more extensible in higher twist coefficients. Sirospun yam is more extensible and less hairy than two-ply yam, too. The SiroSpun process on the ring spinning machine reduces investment costs. Moreover production, energy and air-conditioning costs involved, the organisation of the mill is also greatly simplified by eliminating the twisting department.