Abstract: The PQF(Premium Quality Finishing)pipe mill has been so far regarded as the most technologically advanced retained-mandrel pipe mill.And up to now,three sets of such mills have been set up,and put in operation at Tianjin Pipe(Group)Corporation Co.,Ltd.Briefed in the paper is the development of the roll change-over process of the PQF mill form the original axial change-over(ACO)method to the present lateral change-over(LCO)method.The three TPCO PQF mill lines are also described,covering such aspects as major equipment units,product mix,as well as the features of each mill.The establishment of the three TPCO PQF mills has played a positive role in speeding up further development of both equipment and technological level of domestic tube-making industry.