The　WC　bulk　was　in-situ　synthesized　with　mixed　WO3　+14.5%C　powders　by　spark　plasma　sintering　at　different　temperatures.　The　chemical　valence　state　of　W,　C,　O　in　the　samples　were　investigated　by　XPS.　The　results　indicates　that　the　element　W　changes　from　W+6,　W+5,　W+4　in　oxidative　state　to　metallic　W-0　and　W+2　in　carbide　state　with　the　rising　of　synthesizing　temperature.　It　reveals　that　WO3　is　firstly　reduced　by　carbon　to　form　intermediate　tungsten　oxides　such　as　WO2.72,　WO2,　and　metallic　W　in　the　reduction　process,　then　the　carbonization　reaction　occurs,　and　the　WC　is　formed　finally.