The　multi-principal　element　alloys　(MPEAs),　which　are　also　called　high-entropy　alloys　(HEAs)　or　medium-entropy　alloys　(MEAs)　based　on　the　multi-principal　element　number,　received　intensive　attention　due　to　their　unusual　phase　structures　and　potential　application　in　diverse　aspects.　However,　quantitative　and　graphical　characterization　of　the　atom　distribution,　lattice　distortion,　and　mechanical　properties　are　considerably　insufficient,　which　hinders　the　exploration　and　development　of　the　rich　ore　of　MPEAs.　In　this　work,　a　general　and　comprehensive　approach　was　proposed　to　simulate　the　atom　distribution,　lattice　distortion,　and　mechanical　properties　of　MPEAs　based　on　site　preference,　where　FCC_CoNiV　and　CoCrNi　MPEAs　were　demonstrated　and　compared　quantitatively　and　graphically.　For　this　purpose,　the　temperature-　and　composition-dependent　site　occupying　fractions　(SOFs)　of　MPEAs　were　predicted　using　a　two-sublattice　model　based　on　the　crystallographic　information　of　the　prototype　of　MPEAs,　where　the　corresponding　thermodynamic　database　concerning　the　temperature-dependent　Gibbs　free　energy　of　formation　of　the　involved　end-member　compounds　was　established　in　this　work　using　first-principles　calculations　based　on　density-functional　theory　(DFT)　and　density-functional　perturbation　theory　(DFPT).　For　FCC_CoNiV　MPEA，the　site　occupying　configuration　is　(V1.0000)1a(Co0.4444Ni0.4445V0.1111)3c,　which　is　not　affected　by　the　heat　treatment　temperature,　while　for　FCC_CoCrNi　MPEA,　the　site　preferences　change　continuously　and　slightly　with　the　increase　of　the　heat　treatment　temperature,　for　example,　the　site　occupying　configuration　changes　from　(Co0.3371Cr0.0002Ni0.6627)1a(Co0.3320Cr0.4444Ni0.2236)3c　at　673　K　to　(Co0.3690Cr0.0007Ni0.6303)1a(Co0.3214Cr0.4442Ni0.2344)3c　at　1273　K.　From　the　long-range　ordered　structures,　the　locally　ordered　structures　were　explored　further　by　statistically　analyzing　the　coordination　number　of　the　atom　coordinated　with　the　same　type　of　atoms　in　a　30×30×30　FCC　supercell　based　on　the　prototype　of　L12_AuCu3　which　contains　108,000　atoms.　It　was　found　that　all　the　maximum　numbers　n　for　Co*‐nCo,　Ni*‐nNi,　and　V*‐nV　are　only　8　in　FCC_CoNiV　MPEA,　respectively,　while　the　maximum　numbers　n　for　Co*‐nCo,　Cr*‐nCr,　and　Ni*‐nNi　are　10,　8,　and　10　in　FCC_CoCrNi　MPEA,　respectively.　Thus,　all　coordination　numbers　in　the　studied　MPEAs　are　less　than　12,　i.e.,　the　coordination　number　of　the　pure　metal　with　a　FCC　unit　cell.　The　calculated　relative　lattice　distortion　of　FCC_CoNiV　MPEA　is　2.54%,　which　is　larger　than　that　of　FCC_CoCrNi　MPEA　(2.25%)　by　comparing　the　corresponding　structure　with　and　without　distortion　based　on　the　predicted　site　configuration　at　973　K.　Besides　the　difference　in　the　total　energy,　the　resultant　force　acting　on　each　atom　of　the　FCC_CoNiV　MPEA　with　and　without　distortion　was　graphically　characterized　to　explore　the　mechanism　of　lattice　distortion.　For　the　mechanical　properties,　both　alloys　show　ductile,　while　the　elastic　anisotropic　of　FCC_CoNiV　MPEA　is　larger　than　that　of　FCC_CoCrNi　MPEA,　the　strong　ordering　behaviors　of　V　atoms　may　contribute　to　these　behaviors.　Current　results　agree　well　with　the　limited　experimental　and　simulated　reports　concerning　the　ordering　behavior　of　V　atom　and　ductile　characters.　Thus,　a　general　approach　was　established,　which　can　be　applied　to　simulate　the　atom　distribution,　lattice　distortion,　and　mechanical　properties　of　MPEAs　based　on　site　preference.　We　expect　that　the　current　approach　may　act　as　a　standard　simulating　strategy　on　MPEAs　beyond　the　traditional　random　mixing　consideration　of　the　different　constituent　atoms.　©　2022　Elsevier　B.V.