Abstract: In this paper,a new approach has been made to improve further the accuracy of residual welding stress measurement by the Small Blind-Hole Relaxation Method.The measurement error produced by the hole-side plastic deformation as a result of the stress concentration is also studied.It is discovered that the released strain ε determined in the case of σ>1/2σ_s,is composed of the pure elastic released strain ε_e and the plastic deformation ε_P around the hole.In calculation,ε_p should be subtracted from ε,and the residual stress calculated from ε_e would be the real value.By substituting ε_e for ε according to the improved method,the measurement error has been decreased from 19% to less than 2% when σ approaches σ_s.