Abstract: The PQF pipe mill has been so far the most technologically advanced continuous-rolling mill. The development history of the retained-mandrel continuous-rolling mill falls into two important periods,i.e.,the 2-roll continuous-rolling process (MPM) period and the 3-roll continuous-rolling process (PQF) period. The PQF mill is resulting from modification of the conventional MPM process,and has its roll-change mode developed from the original axially change-over (ACO) to the present laterally change-over (LCO). Elaborated here are the development course and the equipment composition of the PQF mill.