The　crystallization　process　and　crystal　structure　of　the　phase　change　material　TiSbTe　alloy　have　been　successfully　established,　which　is　essential　for　applying　this　alloy　in　phase　change　memory.　Specifically,　transmission　electron　microscopy　(TEM)　analyses　of　the　film　annealed　in　situ　were　used　in　combination　with　selected-area　electron　diffraction　(SAED)　and　radial　distribution　function　(RDF)　analyses　to　investigate　the　structural　evolution　from　the　amorphous　phase　to　the　polycrystalline　phase.　Moreover,　the　presence　of　structures　with　medium-range　order　in　amorphous　TST,　which　is　beneficial　to　high-speed　crystallization,　was　indicated　by　the　structure　factors　S(Q)s.　The　crystallization　temperature　was　determined　to　be　approximately　170　degrees　C,　and　the　grain　size　varied　from　several　to　dozens　of　nanometers.　As　the　temperature　increased,　particularly　above　200　degrees　C,　the　first　single　peak　of　the　rG(r)　curves　transformed　into　double　shoulder　peaks　due　to　the　increasing　impact　of　the　Ti-Te　bonds.　In　general,　the　majority　of　Ti　atoms　enter　the　SbTe　lattice,　whereas　the　remainder　of　the　Ti　atoms　aggregate,　leading　to　the　appearance　of　TiTe2　phase　separation,　as　confirmed　by　the　SAED　patterns,　high-angle　annular　dark　field　scanning　transmission　electron　microscopy　(HAADF-STEM)　images　and　the　corresponding　energy-dispersive　X-ray　(EDX)　mappings.