Abstract: When the PQF mandrel mill is used to produce the Φ273 mm×8 mm L360N seamless steel linepipe,the production is organized with three modes,i.e.,the conventional hot rolling,the controlled rolling and the controlled rolling + controlled cooling (TMCP). An analysis is conducted for the properties and microstructure differences of the pipe as rolled with the said three processes. Relevant industrial test result shows that the steel grain is obviously refined with the TMCP process,which not only improve the tensile properties of the steel pipe,but also significantly enhances the pipe's impact toughness. It is concluded that reasonable TMCP is capable of make the pipe consistently meeting the requirement of -30℃ impact value.