Semiconductor InSb nanowire arrays have been synthesized by the pulsed electrochemical deposition from citric acid aqueous solution into anodic alumina membranes. It was found that the InSb nanowires are of zinc-blende structure, and high filling rate and single-crystalline InSb nanowire array with right stoichiometric composition can be fabricated by proper controlling of the concentration of In and Sb ions and the PH value in the electrolyte and the pulse voltage, and the nanowires have [100] orientation with structure defects such as twins. The optical band gap has a strong blue shift with decreasing the diameter of the nanowire due to the quantum confinement effect.