A modified ring spinning technology has been successfully applied to the production of yarns with reduced twist level and improved performance. Various US cottons and Chinese cottons have been covered in previous studies. In this paper, three combed rovings with different blending ratios of Upland and Extra Long cottons were adopted in a systematic investigation and evaluation on a fine modified ring yarn produced on a new modified spinning system that was developed to reduce the imperfections of fine yarns. The potentially important spinning parameters were proposed and their individual and interaction effects of spinning system parameters on the properties of fine modified ring yarn were quantitatively examined using the response surface methodology. Then with the optimum parameters, physical properties of the yarns and their knitted fabrics produced from three rovings were evaluated by comparing them with the conventional ones. Experimental results showed that yarns produced in the new modified spinning system had reduced imperfections; at low twist levels, fine modified yarns and resultant fabrics also showed improved performance. Moreover, properties of fiber materials and roving quality influenced the properties of modified yarns and knitted fabrics.Institute of Textiles and Clothin