Transition　metal　Mn　ions　are　highly　promising　cathode　dopant　materials.　Due　to　the　introduction　of　Mn　ions,　as　lithium　ions　are　deintercalated,　Mn2+　will　be　transformed　into　Mn3+.　This　situation　will　lead　to　a　severe　Jahn-Teller　effect,　causing　significant　local　lattice　distortion　and　greatly　reducing　electrochemical　stability.　This　article　utilizes　first-principles　calculations　to　investigate　the　doping　of　Mg,　Co,　and　V　to　weaken　Jahn-Teller　effect　in　LiMn0.5Fe0.5PO4　cathode.　The　oxidation-reduction　processes　of　three　doped　models　were　analyzed,　and　the　electronic　structure　and　charge　transfer　amount　between　the　Mn　ion　and　the　O　ion　were　calculated　for　each.　It　was　found　that,　when　Mg　ions　are　doped　into　the　crystal,　Mn　ions　will　stabilize　as　Mn2+,　thereby　weakening　the　Jahn-Teller　effect.　However,　the　addition　of　V　and　Co　will　not　alter　the　Jahn-Teller　effect.　The　differential　charge　density　and　partial　density　of　states　(PDOS)　were　also　calculated.　It　was　found　that　only　the　doping　of　Mg　ions　can　enable　the　material　to　achieve　the　lowest　energy　and　the　smallest　volume　change　rate,　which　attribute　to　weaken　the　Jahn-Teller　effect.　Only　doping　with　V　and　Co　ions　can　achieve　the　highest　lithium　removal　voltage,　increasing　the　average　lithium　removal　voltage　from　4.22　to　4.42　V.　Mechanical　performance　calculations　show　that　the　structures　with　two　types　of　doped　Mg　ion　are　prone　to　shear　deformation　and　cannot　improve　the　ductility　of　the　material.　Additionally,　it　was　found　that　the　migration　barrier　of　the　three　doped　models　was　reduced　to　varying　degrees,　which　is　beneficial　for　the　transition　of　lithium　ions.　Moreover,　the　diffusion　coefficient　of　lithium　ions　also　increased　by　1-4　orders　of　magnitude.