The　released　paper　＇Comments　on　Nano-treatment　of　Surface　Attrition　Via　Historical　View＇　indicates　the　deformation　induced　fine　structure　has　been　studied　since　1970s　to　1980s.　The　so-called　nano　structure　in　recent　years　is　just　renamed　with　new　fashion.　This　paper　attributes　such　＇two　names　for　one　structure＇　dilemma　to　their　measuring　methods.　Dislocation　cell　emphasizes　the　misorientation　angle　while　nano-treatment　is　characterized　in　grain　size,　without　any　restriction　on　angle.　The　dimensions　held　by　the　two　names　are　the　same.　Surface　rolling　is　applied　to　increase　the　misorientation　angle　and　nano　sized　grain　is　realized.　However,　this　so-called　strengthened　surface　is　damaged　worn　surface　30　years　ago.　Regarding　the　effects　of　size　and　angle　on　mechanical　properties,　Hall-Petch　relation　has　taken　as　the　theoretical　base　of　surface　attrition　and　grain　size　is　the　key　factor.　In　fact,　H-P　relation　is　only　an　empirical　rule　summarized　from　conventional　materials　without　theoretical　support.　A　current　study　indicates　that　the　nano　grain　size　shows　little　effect　on　mechanical　property,　while　the　misorientation　angle　plays　a　critical　rule.　Since　Hall-Petch　relation　is　not　valid　for　deformed　structure　with　small　misorientation　angles,　the　base　of　nano-treatment　by　surface　attrition　collapses.　The　main　contribution　of　shot　peening　is　to　improve　fatigue　strength　and　is　widely　accepted　that　the　compressive　residual　stress　playing　a　dominant　role.　Surface　attrition　claims　the　yield　strength　increased　by　fine　structure　retards　crack　initiation,　so　the　fatigue　strength　increases.　However,　no　experiment　confirms　this　mechanism.　In　fact,　the　nano　structure,　produced　by　high　intensity　surface　attrition　creates　micro　cracks,　thus　the　fatigue　crack　initiation　stage　is　skipped.　The　dependence　of　micro　crack　occurrence　and　peening　intensity　is　exhibited.　The　highly　deformed　surface　layer　is　characterized　in　cracked　body　and　thus　should　be　treated　with　fracture　mechanics,　instead　of　continuum　body　by　classical　mechanics.　Some　experiments　separating　the　effects　of　different　factors　on　fatigue　crack　growth　are　introduced.　The　results　show　that　the　compressive　residual　stress　is　the　key　factor　improving　fatigue　strength.　The　factor　of　strain　hardening　by　surface　attrition　achieves　strength　by　scarifying　ductility　leading　to　crack　growth　rate　accelerating.　Therefore,　the　work　hardening　of　surface　attrition　is　detrimental　to　fatigue.　©　2019,　Editorial　Office　of　CHINA　SURFACE　ENGINEERING.　All　right　reserved.