Abstract: The pipeline steel was updated from X70 to X80 through TMCP technique, and its mechanical properties and fracture separation of rolled plate were studied. The results showed that both the longitudinal and transverse tensile strengths of strip specimen are better than those of round bar specimen, and the yield strength of round bar specimen increases first then decreases with increasing coiling temperature. All the values of the work done by impact AkV at -20°C are above 310 J, and all DBTTs are below -100°C. With a series of impact load-displacement curves analyzed, the work done by impact decreases and peak load increases with decreasing testing temperature. Furthermore, as shown by energy spectrometric analysis of impact fracture, the second-phase particles in the vicinity of the fracture surface are mainly of alumina and manganese sulfide.