Three different kinds of zinc oxide (ZnO) nanostructure films have been synthesized on an indium tin oxide (ITO) glass substrate by electrochemical method with adjusting the concentration of the electrolyte, deposition time and temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and photoluminescence (PL) spectrum have been used to determine the characteristics of these nanostructures. The results show that concentration of the electrolyte is one of the most important factors that determine the morphologies of ZnO films. Nanobuds, nanorods, flakes are obtained with the electrolyte concentration increasing. Nanobuds and nanorods have no significant changes with the deposition time prolonged while the flakes grow bigger and thicker. The flakes merge together at high temperature while nanobuds remain unchanged except getting larger and sparser. Nanobuds and nanorods show single crystal patterns while the flakes are composted by multi crystals. The reasons forming such different morphology were discussed according to crystal growth theory. The PL spectra of these ZnO films are quite different according to various microstructures. The film with flake structure has a significant widen near edge emission peak with the depressed visible emission, which may have potential applications on optoelectronic devices and sensors.