Gibbs　free　energy　was　applied　to　analyze　the　carbothermal　reduction　process　of　TiO2.　The　phase　stable　diagram　of　Ti-C-CO　was　drawn,　and　it　can　be　found　that　TiO2　will　be　reduced　to　Ti-O　Magn,li　phase,　TinO2n-1　(3　＜　n　＜　10)　or　Ti3O5　first　and　then　further　reduced　to　TiC.　However,　in　the　present　study,　it　was　found　that　Ti4O7　can　be　reduced　to　TiC　directly　when　the　temperature　was　lower　than　800　K　and　lg(p　(co)/p　(theta)　)　＜　-1.1.　The　reduction　route　was　proved　by　the　results　of　non-isothermal　TG-DTA　combined　XRD.　The　isothermal　analysis　of　carbothermal　reduction　process　of　TiO2　via　TG-DTA　under　the　temperature　of　1363,　1413,　1463　and　1513　K　was　performed.　The　whole　reduction　process　was　divided　into　two　sections:　Initially　it　was　rate　controlled　by　an　interfacial　reaction,　and　later　was　rate　controlled　by　three-dimensional　diffusion.　The　modified　mathematical　expressions　were　deduced.　They　fit　the　experimental　curves　well.　Their　activation　energy　of　steps　was　241.1　and　323.4　kJ　mol(-1),　respectively.