The　ordering　behavior　of　the　L1(2)　type　Co3Ti-based　intermetallics　were　studied　by　using　the　sublaftice　model　supported　with　first-principles　calculations.　The　results　show　that　the　stoichiometric　intermetallics　Co3Ti　is　fully　ordered　intermetallics,　where　Co　atoms　always　occupy　the　3c　sublattice　and　Ti　atoms　always　occupy　the　la　sublattice.　For　ternary　alloy　Co72Ti24M4,　where　x(Co)/x(Ti)=3:1　and　M　represents　the　ternary　alloying　element,　when　M　represents　Si,　Ta　or　Ti　atom,　M　occupies　la　sublattice,　while　when　M　represents　Cu,　Ni,　Pd,　Rh,　V　or　W　atom,　M　occupies　3c　sublattice,　and　when　M　represents　Al,　Cr,　Ge,　Mn,　Sc　or　Y　atom,　M　occupies　both　la　and　3c　sublattices.　The　site　preferences　of　these　alloying　elements　are　independent　of　the　heat　treatment　temperature.　While　the　site　occupancy　of　ternary　alloying　element　Fe,　Hf,　Mo,　Nb,　Ru　or　Zr　in　ternary　alloy　Co72Ti24M4　varies　with　the　heat　treatment　temperature.　With　the　increase　of　extranuclear　electrons,　the　site　preference　of　the　transition　metal　tends　to　change　from　la　sublattice　to　3c　sublattice　gradually.　The　sublattice　occupancy　fractions　varying　with　alloy　compositions　and　temperature　were　also　calculated　in　some　other　Co3Ti-based　alloys　where　x(Co)/x(T)　offsets　3:1.　The　predicted　results　are　consistent　with　most　of　the　literatures,　and　some　disagreements　in　literatures　were　clarified.