Abstract: Analyzed in the paper is the concentric linkage mechanisms of the mandrel bar steadier of the mandrel pipe mill. Addressing the problem that after a product mix expansion-aiming modification of a certain mandrel pipe mill，its mandrel bar steadier fails to meet the modification requirement，the bar steadier proper is modified by means of changing the supporting position of the drive roller，and increasing the length of the drive arm. Furthermore，a simulation analysis of the pre-modification bar supporting scheme and the post-modification bar suppor-ting scheme is performed. As a result，it is revealed that the modified bar steadier is well suitable for the heavier mandrel bars so as to meet the requirements of the product mix expansion-aiming modification of the mill line.