Aluminium-doped zinc oxide (ZAO) nanocrystals with uniform size, high purity and good degree of crystallinity were prepared by an ultrasonic-microwave assisted method. The structure, optical properties and morphologies of ZAO nanocrystals were characterised by X-ray powder diffraction, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy, while the photocatalytic and anticorrosive effects of the product were studied by the degradation test of rhodamine B and salt spray corrosive test, respectively. The effects were quite satisfactory.