Cyclic　voltammetry　pretreatment　of　Pt-based　electrocatalysts　has　been　proven　to　be　a　normal　activation　process　on　achieving　the　optimal　alkaline　hydrogen　evolution　performance.　Until　now,　the　congruent　relationship　between　the　microstructural　evolution　and　performance　improvement　during　this　process　has　rarely　been　reported.　Herein,　when　the　in　situ　transmission　electron　microscopy　and　in　situ　Raman　analyses　are　employed,　a　self-reconstruction　process　from　crystalline　NiS　into　amorphous　nickel　hydroxide　hydrate　[Ni(OH)(2-x)H2O,　where　x　approximate　to　0.3]　on　the　surface　of　platinum-nickel　nanowires　has　first　been　captured,　which　is　the　critical　water　dissociation　active　site　to　offer　a　sufficient　proton　supply.　Furthermore,　such　a　surficial　reconstruction　triggers　an　increase　in　the　current　density　from　-2.3　to　-38.8　mA/cm(2)　(at　-70　mV),　which　is　nearly　17　times.　These　observations　point　to　the　fact　that　it　is　essential　to　consider　the　fundamental　mechanisms　of　hydrogen　evolution　on　the　active　sites　when　the　process　is　scaled　up.