The phase one M-type coke oven in Baosteel was a large coke oven imported from Nippon Steel & Sumitomo Metal, which played an important role in the development of large-scaled coke ovens in China. By investigating the shutting down process and the damage process of M-type coke oven body in Baosteel, the damage of used refractories in different parts, including carbonation chamber, combustion chamber, oven top, regenerative chamber, rising pipe, flue pipe and so on, was investigated and analyzed, which laid a good foundation for further damage analysis of coke oven body and improvement of maintenance in daily production.