In　order　to　find　out　how　much　a　relief　groove　can　change　the　stress　distribution　in　a　shaft,　In　this　paper,　finite　element　technology　and　test　technique　have　been　used　to　study　the　stress　concentration　dates　caused　by　a　escape　by　different　shaft　models.　Their　diameters　are　all　less　than　M30mm.　The　research　solutions　show　that　the　stress　concentration　coefficients　caused　by　the　escapes　grow　with　the　increase　of　the　diameters.　The　pressure　on　the　shaft　should　be　reduced　to　about　0.68　times　of　the　normal　one　so　that　the　shafts　have　the　same　lifetime　as　before.　Stress　concentration　coefficient　is　the　only　parameter　to　estimate　the　stress　concentration　degree.　The　calculate　dates　were　compared　with　the　test　one　in　this　paper　in　order　to　check　the　model＇s　accuracy.　The　conclusions　show　that　the　error　rate　is　less　than　5%.It　can　be　taken　as　a　new　method　to　replace　the　destructive　test　in　the　design　products.　©　(2014)　Trans　Tech　Publications,　Switzerland.