Aggregation　of　Y2O3　particles　with　relatively　large　size　along　grain　boundaries　is　a　main　limiting　factor　for　performance　improvement　in　W-Y2O3　alloys.　In　order　to　tailor　the　distribution　and　achieve　size　refinement　of　Y2O3　dispersoids,　W-Y2O3　alloy　was　prepared　using　ball　milling　with　extended　milling　time　and　subsequent　spark　plasma　sintering　(SPS)　in　this　study.　Microstructure　evolution　of　Y2O3　during　the　preparation　process　was　characterized　in　detail　using　X-ray　diffraction　(XRD),　scanning　electron　microscope　(SEM)　and　transmission　electron　microscope　(TEM).　Mechanical　properties　of　SPSed　alloy　were　evaluated　in　terms　of　microhardness,　three-point　bending　and　compression　tests.　Structure　transformation　of　Y2O3　from　BCC　to　FCC　during　the　process　of　ball　milling　and　subsequent　sintering　was　first　identified　in　W-Y2O3　alloy　in　this　study.　Compared　with　the　raw　micron　sized　Y2O3　powders,　the　transformed　Y2O3　dispersoids　experienced　significant　size　refinement.　Around　76%　of　the　nanosized　Y2O3　dispersoids　were　distributed　inside　grain　interior,　and　they　exhibited　semi-coherent　relationship　with　tungsten　matrix.　These　microstructural　characteristics　contributed　to　the　high　compressive　strength　of　1804.2　MPa　and　microhardness　of　625.7　HV　in　the　SPSed　W-Y2O3　alloy.