The Ni-based reticular MnOx catalytic materials with high porosity and high specific area were prepared by the electrodeposition method. XRD and SEM were employed to characterize the phase structure and morphology of the MnOx films before and after heat treatment. The phase structure has changed from irregular amorphous structure to compacting crystal structure on the effect of heat treatment. The results show that the phase in the film is γ-MnO2 after aging. The electrodeposition mechanism of MnO2 has also been studied in this paper. MnO2 was deposited by the hydrolysis reaction of Mn2+ in electrolyte and the disproportionation reaction of unstable Mn3+ ions. A large number of hydrogen was released during the whole deposition process.