An optical imaging diagnostic system was developed for “QiangGuang-I” wire array Z-pinch experiments. The system, with a gate of 5 ns and spatial resolution of 6.5 lp/mm, is sensitive to the wavelength of 365~750 nm. The system can be used to study the whole process of wire array Z-pinch, from the discharge of single wire to the breakdown of plasma column. The last image series of wire array Z-pinch plasma measured by this system are shown and phenomenally discussed.