In oxygen blast furnace, the lower coke ratio and the higher coke load make the skeleton coke more outstanding. To understand the dissolution of coke in melting and dripping zone, the dynamic dissolution of coke with slag in the condition of different FeO content (5%,10%,15%,20%), different temperature (1400℃, 1450℃, 1500℃) and different time (15min,30min,45min,60min) were carried out. Meanwhile, the three factors and three levels orthogonal were experimented. The dissolution degree were characterized by the weight loss rate and changes in diameter. The results showed that, with the increase of FeO content, temperature and time, the weight loss rate increased and the diameter decreased. Orthogonal showed that time is the biggest factors on coke dissolution , FeO content of the second, and finally the temperature. The microstructure of coke after reaction indicated that the dissolution occured on coke surface and did not go inside.