In the present work, the Fe nanoparticles were synthesized via a novel method one-step reduction method. The excessive citric acid helps to obtain pure and high crystallinity α-Fe and the appropriate temperature (at 620 _oC). The Fe nanoparticles were carefully characterized by the X-ray diffraction, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The morphological characterization indicates that the Fe nanoparticles present spherical shape with diameter of 30 nm. The magnetization hysteresis loops reveal the high saturation magnetization (Ms=198.97 emu/g) and the good ferromagnetic behavior of the magnetic materials. The one-step reduction method for nanoparticles synthesis has the advantages of controllable, short process, large-scale production, and will be an important method of producing nanoparticles.