The exchange coupled dense nanocomposite Nd2Fe14B/α-Fe isotropic bulk magnets were prepared by Spark Plasma Sintering (SPS) method. Influence of sintering temperature, time and pressure on the magnetic properties and microstructure was investigated. It is found that the density and magnetic energy product increased with the sintering temperature and pressure increasing; but the coercivity decreased with the temperature or time further increasing. After sintered at 700 ℃, 500 MPa, and held for 3 min, dense bulk magnets with fine grains of about 20 nm were achieved, whose magnetic properties were: Br=0.81T , Hci =856 kA·m-1, (BH)m =106 kJ·m-3; the density was 7.6 g/cm3.