Several 93W-4.6Ni-1.9Fe-0.5Co alloys have been prepared by liquid phase sintering in vacuum atmosphere using powders with different contents of carbon and oxygen. The microstructures and mechanical properties of sintered samples have been investigated. Results show that the carbon in the starting powders has a stronger deoxidization ability in the high temperature vacuum sintering process due to the carbon-oxygen reaction, which decreases the contents of carbon and oxygen in the sintered samples and prevents the formation of carbide and oxide inclusions, resulting in a strong interfacial boundary between tungsten and bonding phase. The mechanical properties are improved significantly when the oxygen content is controlled to be lower than 500 mg/g