Carbon coated Fe3O4 composite (Fe3O4@C) with bi-morphological architecture has been prepared via a chemical vapor deposition at 450 °C from Fe2O3 nanoparticles by using acetylene as the deposition vapor and carbon source. The Fe2O3 are fully reduced to Fe3O4 in a 10 min of deposition, showing submicron-sized octahedral Fe3O4 particles coated partially with a thin carbon layer mainly, and a few nano-sized Fe3O4 particles coated with carbon also. The deposition period of 20 min results in a further growth of the octahedral Fe3O4 particles and a reduction of the number of the nano-sized ones, correlating to a thick and fully coated carbon layer. Impurities of iron carbides generate in the composite with further prolonging the deposition to 30 min. The Fe3O4@C composite from 20 min of deposition shows superior electrochemical property to others. An initial reversible capacity of 570 mAh g−1 is obtained and the capacity fading is less than 5% after 60 cycles. The fabrication method is facile and time-saving. Such submicron size-predominated Fe3O4@C composite is hopefully not only favorable in alleviating the agglomeration of the iron oxide during cycling, but also helpful in getting high packing density of the anode material.