Abstract: In order to accurately predict the remaining life of a gas pipeline which runs at different stress ratios, a new method of predicting the remaining life of flaw pipeline steels, namely, one-parameter fatigue life prediction method, at different stress ratios was proposed based on fatigue crack growth rate tests. The method considered the destruction effect created by different stress ratios during the running. The remaining life of X52 steel as an example was predicted under the condition of simulating the nature gas running (R=0.1 and R=0.6 by turns).