Fe 3 O 4 nanoparticles with different morphology such as sphere, nanowire, biscuit-like and quasi-cube were successfully prepared using a simple hydrothermal method. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results showed that the morphology of product can be adjusted by changing the reaction conditions such as reaction time, different amount of surfactant added and the addition of organic solvent. In addition, the possible mechanism for the formation of different morphology under the corresponding reaction condition was suggested.