In order to investigate the possibility of improvement of the open end spinning machine which has higher productivity and is more economical than the existing ones, 5 kinds of new open end spinning equipments were designed and operated to produce cotton yarns. The two of those five, enclosed rotor with grooved twister and open rotor with grooved twister, were operated only to produce yarns of Ne 8.5, Ne 4.0 respectively. The quality of both yarns were inferior. The other three types of five, the closed rotor, the closed rotor with radial twister and closed rotor with pinned twister, were operated to produce cotton yarns of Ne 11.0, Ne 11.9 and Ne 10.5 respectively. The quality of produced yarns with these three equipments was fairly good and acceptable.