In this work, different morphologies of copper oxide nanostructures such as nanofibers, nanospindies, nanocones and nanobricks were successfully synthesized by microwave-assisted method. The as-prepared copper oxide nanostructure materials were characterized by various techniques, including field-emission scan electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD) and UV-vis absorption spectroscopy (UV). Experimental results showed that the intensity and the time of microwave irradiation, especially the intensity, played critical roles in the formation of the products. The possible formation mechanism of the nanostructures is also discussed.