The　synthesis　of　tungsten　nanopowder　plays　a　key　role　in　the　preparation　of　the　relevant　alloys.　In　this　paper,　the　nanopowder　tungsten　were　prepared　by　liquid　N2　freezing,　freeze　drying,　and　two-stage　reduction.　The　particle　size　of　the　powder　produced　is　about　30　nm.　The　transformation　in　phase　composition　during　the　producing　process　of　nanopowder　was　studied　by　XRD.　The　appearance　of　freeze-dried　powder,　first-reduced　powder,　and　nanopowder　was　analyzed　by　SEM　and　FESEM.　It　is　proven　that　most　of　the　powder　exist　in　the　non-hygroscopic　and　non-crystalline　state.　And　the　final　product　of　the　experiments　is　the　tungsten　powder,　which　exists　in　the　form　of　crystalline　state.　The　result　of　IR　analysis　indicates　that　the　freeze-dried　powder　remains　Keggin　structure.　In　addition,　through　TG　and　DTA　thermal　analysis,　it　is　shown　that　the　loss　process　of　water　contained　in　the　powder　could　be　divided　into　three　stages.