Ceramic films were prepared on pure aluminum plates using both constant and step voltages to study the effects of different voltage modes on the microstructure and properties of the ceramic film layers. Utilizing scanning electron microscopy, X-ray diffraction, microhardness testers, and electrochemical workstations, the micro-morphology, phase composition, microhardness, and corrosion resistance of the ceramic film layers on pure aluminum plates were examined, while the formation mechanism of these layers was analyzed. The results showed that the ceramic film layers on the pure aluminum plates were amorphous Al2O3 phases. Compared to constant voltage, the step voltage method resulted in fewer pores, cracks, and other defects in the ceramic films. The microhardness of the ceramic film layers reached its maximum at 26 V for both constant and step voltages, registering 520.2 HV and 570.2 HV, respectively. At a step voltage of 26 V, the ceramic film exhibited optimal corrosion resistance, with a corrosion potential of -0.429 V and a polarization resistance of 113 173.9 Ω. When applying step voltage to prepare the ceramic film layers on pure aluminum plates, each voltage increase accelerated the chemical reaction rate, resulting in a dense and uniform internal barrier layer on the surface, thereby enhancing the microhardness and corrosion resistance of the ceramic film layers.