Abstract: Fatigue life prediction under variable amplitude loading is an important issue in the integrity analysis of welded structures. Based on the fatigue damage zone concept proposed by Pavlou and the S-N curve recommended in BS7608 standard, an approach to predict fatigue lives of welded structures was realized by FEA heat transfer problem. Fatigue tests under two-level tensile loading block sequences were conducted for load-carrying cruciform welded joints, non-load- carrying cruciform welded joints and butt welded joints, respectively. The fatigue lives of the specimens were estimated according to Miner model, M-H model and Pavlou method. Results showed that the Pavlou method had higher prediction accuracy with more uniform distribution in the error scatter diagram of predicted life versus test life, which validated the rationality and effectiveness of the proposed method. Moreover, the influence of S-N curve survival probability on the life prediction accuracy is discussed. The S-N curve with 2.3% survival probability is suggested to be utilized to obtain satisfactory prediction results.