With　adding　various　contents　of　combined　grain　growth　inhibitors　(GGI)　VC　and　Cr3C2　into　the　ultrafine　WC-Co　composite　powder,　the　effects　of　the　GGI　addition　on　the　phase　constitution,　microstructure　and　mechanical　properties　of　the　cemented　carbides　have　been　investigated　by　X-ray　diffraction　(XRD),　scanning　electron　microscopy　(SEM)　and　transmission　electron　microscopy　(TEM),　respectively.　The　result　shows　that　with　the　content　of　GGI　increasing　in　the　composite　powder,　the　abnormal　grain　growth　disappears　and　homogeneous　ultrafine　grain　structure　forms.　The　hardness　of　cemented　carbides　can　be　improved　effectively　with　increasing　the　addition　of　VC,　while　enhancements　of　the　transverse　rupture　strength　(TRS)　depends　more　on　the　Cr3C2　addition.