Abstract: The influence of Sb on the C solubility in liquid Fe was measured under 1300,1400 and 1500℃.The C solubility decreases with the increase of Sb content in liquid Fe.The tem- perature dependences of the first order interaction coefficients in C-saturated liquid Fe were determined as follows: *e_C~(Sb)=11.309/T+0.0025 *e_(Sb)~C=128.023/T-0.0219 The temperature dependences of interaction coefficients between Sb and C in dilute liquid Fe were given to be: e_C~(Sb)=14.204/T+0.025 e_(Sb)~C=120.541/T+0.227 ε_C~(Sb)=ε_(Sb)~C=6026.75/T+11.958 The interaction coefficients at 1600℃ are *e_C~(Sb)=0.0085,e_C~(Sb)=0.033,*e_(Sb)~C=0.295, ε_C~(Sb)=ε_(Sb)~C=15.36.The first order interaction coefficients vary slightly with the temperature.

Key words: Fe-C-Sb solution, C-Sb interaction, solubility method, iso-activity method