Abstract: The fatigue performance of weathering steel SMA490BW butt welded joints, one-time repaired joints, two-times repaired joints were tested by MTS-810 fatigue testing machine. The mean S-N curve and P-C-S-N curve(P=95%, C=75%) were obtained. Effect of welding repair on fatigue properties of welded joints was studied. The fatigue results showed that welding repair has no obvious effect on the fatigue performance of the welded joints. Took the three sets of data together as a sample, fatigue curve was obtained by using the group method and the lifting method. The Goodman-Smith fatigue limit diagram figure was drawed by eight node method, which can provide the basis for the fatigue strength analysis of car bogie.