Localized electrochemical deposition is a micromachining approach which exhibits great potential in fabrication of various microstructures due to its simplicity, low cost and reproducibility. Upon applying ultrashort voltage pulses, electrochemical reactions can be spatially confined with nanometer accuracy, which permits for high precision machining of electrochemical active materials including metals and semiconductors. Cu2O has been extensively investigated for its appealing electronic and optical properties, with a direct bandgap around 2.0 eV, a high absorption coefficient as well as abundance. Recently, more researches have focused on Cu2O-based optoelectronic and photochemical devices such as photocathodes for photoelectrochemical water splitting. Electrodeposition is a common method for the preparation of Cu2O, which has advantages of inexpensiveness, low reaction temperature and ease of control. However, Cu2O in micro-size can not be prepared by traditional electrodeposition. Using localized electrochemical deposition with ultrashort voltage pulses, Cu2O in micro-size can be fabricated. At present, Cu2O microstructures prepared by localized electrochemical deposition with ultrashort voltage pulses has not been reported yet. In this paper, Cu2O microdisks were successfully fabricated by localized electrochemical deposition with nanosecond ultrashort voltage pulses. A visualized processing system based on a four-electrode configuration for localized electrochemical deposition with ultrashort voltage pulses was developed. In a miniature cell, an indium tin oxide (ITO) covered glass was used as the working electrode. A Pt wire and an Ag/AgCl were functioned as the counter electrode and the reference electrode while a 50 μm diameter Pt/Ir wire with its front face polished was used as the microelectrode. Solution of 0.4 mol/L CuSO4+ 3 mol/L C3H6O3 with pH adjusting to 11 was used as electrolyte. Local polarization was induced through applying nanosecond ultrashort voltage pulses generated by a pulse generator between the microelectrode and the working electrode. The potential of the working electrode and the microelectrode were controlled by a Bi-potentiostat. An in situ inverted optical microscope was used to monitor the dynamic process of localized electrochemical deposition in real time. Morphology of Cu2O deposited with different conditions was characterized with a scanning electron microscopy (SEM). The effects of processing parameters, including electrodes interval, pulse length and microelectrode removed velocity on the size and morphology of the deposited Cu2O were investigated. The results in this paper showed that electrodes interval, pulse length and microelectrode removed velocity had significant effects on the diameter and morphology of the deposited Cu2O microdisks. As the electrodes interval increased, the diameter and the grain size of the deposited Cu2O microdisks both decreased. The shorter the voltage pulse length, the smaller the area of the Cu2O microdisks. The faster the microelectrode moved, the smaller the diameter of the Cu2O microdisks and the worse the crystallinity. Well-defined deposited Cu2O microstructures could be obtained using electrodes interval of 14 μm, pulse length of 30-40 ns and low microelectrode removed velocity. In conclusion, Cu2O microdisks with a diameter of 50-100 μm were successfully deposited on the surface of ITO substrates by localized electrochemical deposition with nanosecond ultrashort voltage pulses, which provides a simple and effective method for micromachining high-efficiency Cu2O-based optoelectronic devices.