Abstract: By using low stretch Nylon filament yarn and spun silk roving,the spun silk/Nylon filaments sirofil composite yarns were spun with various twists and feeding distances between Nylon filaments and spun silk roving at front roller.The tensile properties,yarn evenness and hairiness of sirofil composite yarn were measured.By variance analysis,it was concluded that the breaking strength and elongation at break of composite yarn increase with increasing of twist,but little dependence on the feeding distance;no significant effect is observed on the composite yarn evenness by the twist and feeding distance;and the hairiness of composite yarn lessenes with the increasing of both twist and feeding distance. The optimized spinning parameters for the sirofil composite yarn in the spinning experiments were obtained: 850 twist/m and feeding distance at front roller of(18 mm.)