Abstract: The carbonyl iron/cobalt phthalocyanine composites were obtained while the solution of carbonyl iron and cobalt phthalocyanine (CoPc) mixing into DMF was backflowing for 3 hours at 114 ~120℃ composite in situ . Composite particles were analyzed using XRD, SEM, TG and DTA. The result shows that the composition and structure of the Fe/CoPc composites are different using various methods of synthesis. The lower the concentration of carbonyl iron decomposing and forming Fe particles, the smaller the average diameter of composites. The surface of the Fe/CoPc composites is covered completely by CoPc, they are almost regular spherical shape and their diameter is of 1.20μm±0.10 μm when the mass content of CoPc in the backflow solution is above 6.7%. Density of the composites is cut down to 3.664 g/cm³ and anti oxygenation of ultramarinen Fe particles in the composites is advanced obviously.