The corrosion furnace hearth was made a macroscopical investigation and microscopical analysis after blast furnace was shut down. Results indicate that the carbon brick between the tap holes is the most seriously corroded, the brittle crack zone is evidently existed on the hot side of carbon brick, and the chemical composition in the hearth is different. Researches find that the long campaign life of No.2 BF in Baosteel owe to the high thermal conductivity hearth and protection of the solidified pig iron layer on the refractory surface, and the main reasons of hearth corrosion are heat stress and carbon dissolution of carbon brick.