Abstract: Tensile test and three point bending fatigue test of X80 pipeline steel were carried out, and the tensile farcture and the effect of different stress ratios(0.1,0.4,0.6) on fatigue crack growth behavior were studied. The results show that X80 pipeline steel has the characteristics of continuous yielding and dimple tensile fracture. Increasing stress ration can decrease the fatigue life and the crack length of X80 steel. Paris′s law can well fit the fatigue crack growth rate of X80 pipeline steel at differnt stress ratios with stress intensity factor amplitude ΔK as driving parameter.