Existing　magnetic　dipole　models　cannot　provide　the　accurate　prediction　result　of　the　effect　of　the　stress　on　the　magnetic　flux　leakage　(MFL)　induced　by　defects　in　ferromagnetic　materials.　To　solve　this　problem,　an　improved　dipole　model　is　proposed　to　investigate　the　stress-dependent　MFL　in　tensioned　specimens　of　Q235　steel.　The　stress　concentration　around　the　defect　of　a　cylindrical　through-hole　leads　to　heterogeneous　distribution　of　magnetization　along　the　defect　surface.　Classic　Timoshenko＇s　theory　is　used　to　solve　the　localized　compressive　stress　and　tensile　stress　around　the　defect.　The　J-A　model　is　employed　to　determine　the　stress-dependent　magnetization　distribution,　which　is　the　key　parameter　in　the　magnetic　dipole　model.　The　stress-dependent　MFL　signals　predicted　by　the　improved　model　are　well　consistent　with　the　results　of　verification　experiments　and　the　peak-to　peak　amplitude　of　the　normalized　MFL　signal　demonstrates　the　parabolic　dependency　on　the　applied　tensile　stress.　A　stress　increment　of　100　MPa　can　increase　the　amplitude　of　the　MFL　signal　by　24%,　which　may　cause　a　significant　error　in　defect　sizing.　The　proposed　improved　magnetic　dipole　model　can　reveal　the　effect　of　the　stress　concentration　on　the　induced　MFL　signals　and　it　is　also　applicable　to　solve　the　inverse　problem　for　estimating　the　shapes　and　sizes　of　the　defects　even　though　the　stress　is　involved.