In order to ensure the quality of finished steel on the premise of cost control, the control of alloy element yield is regarded as a key content of deoxidizing and alloying process in iron and steel enterprises. The influencing factors of alloy element yield in deoxidizing and alloying of molten steel were studied. Firstly, on the basis of historical real data, the yield of C and Mn was calculated according to steel grade and converter terminal temperature. Secondly, factor analysis method was used to select 13 possible influencing factors for C and Mn, and SPSS software was used to establish the factor analysis model of influencing factors for C and Mn. Five and four factors for the two elements were obtained respectively, and each factor was explained according to relevant chemical principles. At last, it is concluded that the main factors influencing alloy element yield in deoxidizing and alloying of molten steel are the deoxidizing ability of added material, the content of corresponding element in added material, the amount of alloy additive and external conditions.