Ordered L1_0 to FePt nanoparticles are strong candidates for high density magnetic data storage media because the L1_0 phase FePt has a very high magnetocrystalline anisotropy (K_usim6.6-10times107erg/cm3), high coercivity and chemical stability. In this study, the ordered L1_0 FePt nanoparticles were successfully fabricated by chemical vapor condensation process without a post-annealing process which causes severe particle growth and agglomeration. The Fe_50Pt_50 nanopowder was obtained when the mixing ratio of Fe(acac) and Pt(arac) was 2.5 : 1. And the synthesized FePt nanoparticles were very fine and spherical shape with a narrow size distribution. The average particle size of the powder tended to increase from 5 nm to 10 nm with increasing reaction temperature from 800°C to 1000°C. Characterisitcs of FePt nanopowder were investigated in terms of process parameters and microstructures.