The residual stress of T-joints for SUS304 stainless steel by YAG laser welding was measured by the method of hole-drilling,and the effects of heat treatment and hardness distribution of weld joints on the distribution of residual stress for T-joints were analyzed.The results showed that the maximum of longitudinal residual tensile stress for T-joints was about 140MPa.The maximum of residual stress was not more than 40MPa after heat treatment,the peak of residual stress reduced obviously.The gradient of residual stress distribution was also reduced significantly.Strain hardening phenomenon occurred for T-joints,and the hardness of weld and heat affected zone was both higher than the hardness of base metal,the peak of hardness occurred in the fusion line.The effect of strain hardening phenomenon of weld and heat affected zone on the residual stress distribution of T-joints for SUS304 stainless steel was obvious,which made longitudinal residual tensile stress become higher. The residual stress of T-joints for SUS 304 stainless steel by YAG laser welding was measured by the method of hole-drilling, and the effects of heat treatment and hardness distribution of weld joints on the distribution of residual stress for T-joints were analyzed. The results showed that the maximum of longitudinal residual tensile stress for T-joints was about 140MPa. Maximum maximum residual stress was not more than 40MPa after heat treatment, the peak of residual stress reduced obviously. Gradient of residual stress distribution was also reduced significantly.StrainPlasticity occurred occurred in T-joints, and the hardness of weld and heat affected zone was both higher than the hardness of base metal, the peak of hardness occurred in the fusion line. the effect of strain hardening phenomenon of weld and heat affected zone on the residual stress distribution of T-joints for SUS304 stainless steel was obvious, which made longitudinal residual tensile stress become higher.