Based on the survey of two Chinese large blast furnaces (BFs), it was found there were complex relationships between hearth sidewall and bottom temperature. The highest temperature positions for these two BFs were distinctly different, which was indicated that the positions of the most serious erosion were different. Therefore, the mathematical model of molten iron flow in BF hearth bottom was established and the influence of floating state of deadman on molten iron flow and wall shear stress was analyzed. The results showed that the status of molten iron flow was determined by the floating state of deadman so that the erosion position was influenced. The floating height of deadman of BF A was higher than that of BF B obviously, which led to the difference between hearth sidewall and bottom temperature and also the erosion migration. When deadman was sinking at bottom, the molten iron flow was faster and wall shear stress was larger near the bottom corners than that at other bottom positions so that the elephant-foot-type erosion occurred easily. When deadman was floating, the erosion position migrated from the hearth bottom corners to the corners between bottom of deadman and hearth sidewall. The permeability of deadman would also affect the erosion. Finally, the erosion profiles and their forming reasons were discussed at different floating heights of deadman.