Abstract: Elaborated are the PQF-LCO mandrel mill with lateral roll-change over function and the PQF-ACO mandrel mill with axial roll-change over function of Tianjin Pipe(Group)Corporation,covering such aspects as the roll-change methods,the equipment compositions,the rolling units and the rolling failure solutions,etc. Also made is a comparative analysis of the said two mandrel mills. Based on the analysis,it is concluded that the separate overall superiorities of the two mandrel mills need to be further verified.