W　alloys　prepared　via　oxide　dispersion　strengthening　have　shown　enhanced　mechanical　performance.　In　this　paper,　W-1.10　vol%　Zr-2.00　vol%　Y2O3　(WZY)　and　W-1.10　vol%　Zr-2.00　vol%　Er2O3　(WZE)　were　fabricated　to　investigate　the　effects　of　formation　of　complex　oxide　dispersions　on　mechanical　properties　and　microstructure　of　multi-doped　W　alloys.　By　controlling　the　atomic　ratio　of　added　ZrH2　and　rare　earth　oxides　through　composition　design,　the　goal　of　complete　formation　of　complex　oxide　particles　with　pyrochlore　structure　(A(2)B(2)O(7))　was　achieved.　Electron　probe　microanalysis　(EPMA)　and　transmission　electron　microscopy　(TEM)　results　showed　that　these　dispersion　particles　in　WZY　and　WZE　were　Y2Zr2O7　and　Er2Zr2O7,　respectively.　Moreover,　microstructure　analysis　showed　that　Er　2　Zr2O7　exhibited　smaller　size,　higher　number　density　and　more　homogenous　distribution　compared　to　Y2Zr2O7,　which　led　to　finer　grains　of　WZE　(0.58　+/-　0.03　mu　m)　compared　to　WZY　(1.34　+/-　0.29　mu　m).　Finer　microstructure　including　smaller　grains　and　dispersion　particles　of　WZE　contributed　to　its　higher　strength　and　better　ductility.　Furthermore,　the　formation　mechanism　of　complex　oxide　dispersion　particles　was　discussed　in　detail.