The　mechanism　research　of　structure-related　reactions　on　Li2MnO3　is　important　to　enhance　the　electrochemical　performance　of　lithium-manganese-rich　layered　oxides.　Although　there　are　some　reports　on　the　structure　evolution　of　Li2MnO3　during　cycling　process,　the　employed　research　techniques　are　very　limited,　mainly　in/ex-situ　X-ray　diffraction,　X-ray　absorption　and　transmission　electron　microscopy.　Here,　atomic　pair　distribution　function,　a　method　to　study　the　local　atomic　arrangement　on　the　basis　of　average　spectroscopic　information,　is　used　for　the　first　time　to　study　the　local　structure　evolution　of　Li2MnO3　during　electrochemical　charge/discharge　cycles.　The　results　clearly　demonstrate　that　Mn3+/Mn4+　redox　couple　is　activated　and　Mn　ions　are　reduced　during　discharging　process.　Some　Mn　ions　in　Mn　layers　can　significantly　migrate　to　Li　layers　and　occupy　the　octahedral　sites.　As　a　result,　a　portion　of　inserted　Li　ions　can　occupy　the　face-shared　tetrahedron　sites,　accompanied　by　the　formation　of　local　spinel-like　structure.　This　work　provides　an　important　and　suitable　method　based　on　the　average　spectroscopic　information　to　investigate　the　local　structure　of　electrode　materials　of　lithium-ion　batteries　as　well　as　other　advanced　battery　systems.　(C)　2019　Science　China　Press.　Published　by　Elsevier　B.V.　and　Science　China　Press.　All　rights　reserved.