The bare spandex fabrics produced by RFSM seamless underwear machine through intelligent and advanced spandex control system and combined with high needle distance knitting components, are featured at soft texture, delicate feeling, smoothness and brightness. The fabrics produced in combination with pure cotton, colored cotton, modal and other face yarns ensure good hygroscopicity and gas permeability, dangling and floating, with excellent elasticity and extension performance to maximize the curvature of human body, and sculpt the sexy and charming beauty of women, which serves as future development trends of knitted underwear.