Abstract: In order to control the non-metallic inclusions in producing of rail steel with high cleanliness for 350 km/h,the research in control technique of non-metallic inclusions was carried out systematically.The removal ratio of non-metallic inclusions increased remarkably by adopting proper blowing argon mode at ladle bottom and optimum composition of ladle slag,and the T[O] reduced about 40%.The shape and composition of the inclusion was controlled effectively by modifying sulphide.After applied the control techniques in the production of rail steel with high cleanliness for 350km/h,the T[O]in steel rail reduced to 10.17×10^-6,A type inclusion ≤ 2.0 grade,B,C and D type inclusion ≤ 1.0 grade,which could meet the requirement of technical indexes for high speed steel rail,and made Panzhihua Iron and Steel Company become the first enterprise at domestic could produce rail steel with high cleanliness for 350 km/h in mass scale.