Abstract: The bead-on-plate samples were treated by TIG dressing, burr grinding and needle peening on weld toe respectively. The low-cycle fatigue tests were taken by four points bending on these samples with different treatments including samples after welding. The residual stresses were measured on these samples. And the stress concentration factors with different treatments were calculated. The results indicate that the TIG dressing treatment can improve the low-cycle fatigue ability obviously. The fatigue life increased 98% averagely. The burr grinding treatment didn't improve the low-cycle fatigue ability notably. The needle peening treatment could improve the low-cycle fatigue ability to a certain extent. But the improving effect of the needle peening treatment was less than the TIG dressing treatment. The fatigue life increased 45% averagely. The results which indicate that the stress concentration is the main factor influencing the low-cycle fatigue ability of weld joints. The effective approach of improving the low-cycle fatigue ability of weld joints is to reduce the stress concentration factor.