Functionally graded material (FGM) with density gradient has showed great potentials as flier-plate for creating quasi-isentropic compression waves. In order to obtain a FGM with low density in the front face and with a wide density range, the Mg-W system gradient material is designed, and the power metallurgy method and hot-press (HP) sintering are chosen for its fabrication. The sintering of Mg-W alloys is studied at relative low temperatures and the processing of densification is mainly investigated. It is found that, up to 85wt%W, the approximately wholly dense Mg-W system alloys are achieved at 620°C for 1.5 hours under a pressure of 100MPa. Mainly the mechanical mixtures of Mg and W are formed in Mg-W alloys. And the Mg-W alloys are fully densified at 620°C due to the conglutination of Mg, a small amount of which are melting in this experimental condition. Finally, the Mg-W system FGM with a wide density gradient from 1.74g/cm3 to 7.56 g/cm3 within the 3.50mm thickness range is fabricated at the sintering parameter of 620°C-100MPa-1.5hours.