Abstract: In view of the actual situation of Panzhihua Iron ＆ Steel（Group）company（PZHISC）,in order to controlling compositions of ladle slag,a high basic refining slag was added to ladle during the steel being tapped,a modifier was added to ladle after the steel was tapped,also a small number of high basic refining slag and 0.30～0.60 kg aluminum pill per ton steel were supplemented in LF furnace.And the blowing argon time was extended by 6 min after LF refining.The removal conditions of inclusions were improved by these technical measures,the quality of molten steel of low carbon steels was improved substantially.The average total oxygen content is 14.69×10^-6,the average sulphur content is 0.007%,[N]is less than 50×10^-6,non-metallic inclusions of type-B and type-C are less than before,the vast majority of non-metallic inclusions of type- A and type-D both are 0.5 grade in the test slab of low alloy steel.