Rechargeable aqueous zinc-manganese dioxide (Zn-MnO2) batteries are one of promising systems for grid-scale energy storage applications, owing to their favorable merits such as low cost, environmental benignity and intrinsic operation safety. However, these batteries always suffer from poor cycling stability because of the low electric conductivity and poor structural stability of MnO2 cathodes, besides the detrimental dendrite growth and hydrogen evolution corrosion of Zn anodes. In this work, a hydrothermally-prepared Al-doped MnO2 as stable cathode material for aqueous Zn-MnO2 batteries were reported. The effects of Al doping on the phase, morphology, water content and electrochemical performance of MnO2 were systematically explored by X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS) tests. Equipment analyses indicate that Al doping not only transforms the product from micro β-MnO2into nano α-MnO2, but also improves the host material’s crystal water content. When used as cathodes of Zn-MnO2 batteries, the Al-doped MnO2 has a residual capacity of 150.1 mAh?g-1 after 500 cycles at a high current density of 1 A?g-1, much better than the undoped MnO2 (residual capacity=97.8 mAh?g-1 after 500 cycles). This research has certain enlightenment to the development of high-performance zinc-manganese batteries.