Abstract: The reactivity of coke and semi-coke and their interaction have been investigated by conducting the thermogravimetric analysis experiment and simulating the burden reaction in oxygen blast furnace. The experiment shows that the reactivity of semi-coke is superior to that of coke. The semi-coke has two DTG peaks during heating: the first one for the secondary pyrolysis of semi-coke and the second for the coupling reaction of pyrolysis and gasification. The interaction between the semi-coke and the coke appears when the furnace burden is heated to 800 ℃, and as the heating rate increases, their interaction becomes stronger. In the blast furnace conditions, semi-coke can reduce the reaction and pulverization of coke and the erosion of its pore wall by CO₂ and H₂O, which is a good protection for coke.