Abstract: Nanodiamond-vitrified bond composite powder was prepared by polyacrylamide gel(P-G)method. The powder was pressed and sintered at low temperature, and the nanodiamond-vitrified bond composite sample was obtained. Contrast with this method, vitrified bond was also prepared by melting method, then mixed with nanodiamond and sintered at a proper temperature. The phase constitution and microstructure of sintered samples were characterized by X-ray diffraction and field emission scanning electron microscopy. The flexural strength was measured by three-point bending method. The volume density and porosity were tested according to Archimedes' principle. The results show that nanodiamond-vitrified bond composite powder can be obtained by P-G method, and the flexural strength, volume density and porosity of samples sintered at 800 ℃/2 h are 60.41 MPa, 1.81 g/cm³ and 15.67%, respectively. When nanodiamond powder is mixed with vitrified bond matrix mechanically, the flexural strength, volume density and porosity of sintered samples are 46.48 MPa, 2.23 g/cm³ and 11.75%, respectively, and the agglomerate of nanodiamond is clearly observed. P-G method can be used as a new technology for preparing nanodiamond-vitrified composite as ultrafine grinding tools.