It　is　a　long-term　challenge　to　further　improve　the　corrosion　resistance　while　ensuring　the　strength　of　magnesium　(Mg)　alloys.　Revealing　the　effect　of　potential　fluctuation　on　the　micro-galvanic　corrosion　and　the　subsequent　film　formation　is　important　for　understanding　the　corrosion　mechanism　of　Mg　alloys　with　multiple　strengthening　phases/structures.　Here,　we　prepared　the　high-strength　Mg-14.4Er-1.44Zn-0.3Zr　(wt.%)　alloys　containing　hybrid　structures,　i.e.,　elongated　long-period　stacking　ordered　(LPSO)　blocks　+　intragranular　stacking　faults　(SFs)/LPSO　lamellae.　The　Mg　alloy　with　elongated　LPSO　blocks　and　intragranular　LPSO　lamellae　(EZ-50　0　alloy)　obtains　good　corrosion　resistance　(2.2　mm　y　-1　),　while　the　Mg　alloy　containing　elongated　LPSO　blocks　and　intragranular　SFs　(EZ-40　0　alloy)　shows　a　significantly　higher　corrosion　rate　(6.9　mm　y　-1　).　The　results　of　scanning　Kelvin　probe　force　microscopy　(SKPFM)　show　the　elongated　LPSO　blocks　act　as　cathode　phase　(87　mV　in　EZ-40　0　alloy),　and　the　SFs　serve　as　the　weak　anode　(30　mV　in　EZ-40　0　alloy),　resulting　in　high　potential　fluctuation　in　EZ-40　0　alloy.　On　the　contrary,　both　elongated　blocks　and　intragranular　lamellae　are　cathodic　LPSO　phase　(67-69　mV)　in　EZ-50　0　alloy,　leading　to　a　lower　potential　fluctuation.　Quasi　in-situ　atomic　force　microscope　(AFM)　observation　indicates　that　high　potential　fluctuation　would　cause　strong　micro-galvanic　corrosion,　and　subsequently　leads　to　the　failure　in　rapid　formation　of　corrosion　film,　finally　forming　a　loose　and　porous　film,　while　relatively　low　potential　fluctuation　could　result　in　more　uniform　corrosion　mode　and　facilitate　the　rapid　formation　of　protective　film.　Therefore,　we　propose　that　it　is　an　effective　way　to　develop　high-strength　corrosionresistant　Mg　alloys　by　controlling　the　potential　fluctuation　to　form　a　＂uniform　potential＂　strengthening　microstructure.　(c)　2023　Published　by　Elsevier　Ltd　on　behalf　of　The　editorial　office　of　Journal　of　Materials　Science　&　Technology.