The　blind-hole　method　is　the　most　widely　used　approach　to　experimentally　determine　the　distribution　of　residual　stress.　This　paper　aims　to　improve　test　accuracy　of　welding　residual　stress　and　conducts　an　experimental　study　on　the　strain　release　factors　involved　when　using　the　blind-hole　method　for　Q235　and　Q345,　two　steels　commonly　used　in　building　structures.　The　ranges　of　strain　release　factors　A　and　B　in　the　elastic　stage,　the　effects　of　strain　release　factors　on　residual　stress　calculated　values,　and　the　plastic　corrected　strain　release　factors　are　analyzed　considering　of　the　effect　of　plastic　deformation　around　the　blind　hole　on　measurement　accuracy.　Finally,　a　simplified　calculation　formula　to　determine　strain　release　factors　is　proposed　for　use　with　the　blind-hole　method.　Results　show　that　in　the　elastic　stage,　strain　release　factor　A　for　Q235　and　Q345　ranges　from　−0.399　to　−0.525　and　strain　release　factor　B　from　−0.791　to　−0.960.　Changing　the　strain　release　factors　A　and　B　shows　that　calculated　residual　tensile　stress　varies　in　relation　to　a　decrease　in　both　factor　values.　However,　there　is　a　increase　in　calculated　residual　compressive　stress　with　a　decrease　in　the　strain　release　factor　A　value,　but　there　is　an　decrease　with　a　decrease　in　strain　release　factor　B　value.　Calculated　residual　stress　applied　to　elastic　strain　release　factors　is　compared　with　that　applied　to　amended　plastic　strain　release　factors　for　Q235　steel.　The　maximum　deviation　between　calculated　residual　stress　and　test　stress　is　reduced　from　21.1　to　1.0%,　and　for　Q345　steel　from　26.5　to　1.2%.　It　is　thus　evident　that　the　plastic　correction　formula　proposed　in　this　paper　can　be　used　in　calculations　when　conducting　a　residual　stress　test.　©　2017,　Tianjin　University　and　Springer-Verlag　GmbH　Germany.