Steel slag corrosion is one of the main damage forms of refractory during service, and it is hard to observe the actual corrosion process directly. Traditionally, postmortem analysis is used to evaluate corrosion resistance capacity and to understand corrosion mechanism of refractory. However, the lack of process information in postmortem analysis results in deviation. Therefore, on the basis of high temperature visualization system and digital image correlation (DIC) method, three typical steel slags were selected to carry out the corrosion corrosion behavior experiments of alumina magnesia refractory, and the effects of different steel slags and heat treatment temperatures on the corrosion resistance capacity of refractory were discussed. The results show that the slag with lower basicity has more serious corrosion on refractory. The corrosion resistance capacity of alumina magnesia refractory can be effectively improved by heat treatment above 1 000 ℃. The average strain curve and corrosion strain nephogram over time can be obtained through DIC method. The average strain curve is used to compare the corrosion resistance capacity of alumina magnesia refractory to different steel slags, and the corrosion strain nephogram reflects the evolution process of corrosion. The above two provide quantitative indicators for characterizing the slag corrosion process of refractory.