Synthesis　of　ultrafine　WC-Co　powders　was　investigated　using　WO3,　Co3O4　and　graphite　powders　as　starting　materials　by　high　energy　ball　milling　followed　by　reduction　and　carburization.　The　results　show　that　particle　sizes　of　powder　mixtures　milled　30　h　are　in　the　range　of　70-100　nm.　When　the　milled　mixture　is　reduced　in　a　flowing　gas　mixture　of　H2　and　Ar　at　different　temperatures　ranging　from　450　to　700°C　for　2　h,　the　reaction　sequence　of　WO3　to　W　appears　as　WO3-＞WO2.9-＞WO2.72-＞　WO2-＞W　with　the　increase　of　temperature,　and　WO3　reduction　completes　at　700°C.　Reduction　reaction　of　Co3O4　to　Co　can　be　finished　in　2　h　at　450°C　and　the　reduced　Co　keeps　reacting　with　W　to　transform　into　Co3　W　with　the　increase　of　reduction　temperature　and　time.　The　final　product　of　reduction　reaction　is　composed　of　W,　Co,　Co3W　and　graphite.　The　reduced　mixture　is　carburized　in　a　flowing　Ar　in　temperature　range　of　700-1000°C,　carburization　reaction　takes　place　following　the　routine　W(Co3W)-＞Co6W6C-＞　Co3W3C-＞W2C-＞WC,　and　the　carburization　reaction　completes　at　900°C　in　2　h.　The　size　of　the　WC　grain　in　the　final　WC-Co　composite　powders　is　in　the　range　of　200-300　nm.