Although coal gangue as solid waste is used in electricity generation, coalmine backfilling and building materials, its utilization rate is still not high. How to improve the high-value utilization of coal gangue has become a research hotspot. In this paper, Al2O3-SiO2 aerogel powder was synthesized by one-step acid leaching followed by sol-gel method and ambient pressure drying from coal gangue. Ultrasonic was exerted in the process of solvent replacement and modification. The structure and performance of Al2O3-SiO2 aerogel powder were characterized by means of BET, XRD, SEM, FT-IR, TG-DSC and contact angle measurement. The results show that the reaction rate is accelerated by ultrasonic and the preparation cycle is shortened. Al2O3-SiO2 aerogel is a mesoporous material with three-dimensional network structure of nano. Al2O3-SiO2 aerogel has a minimum bulk density of 0.120 g/cm3 and a specific surface area of 635 m2/g, its shrinkage at high temperature is lower than that of SiO2 aerogel prepared from sodium silicate, Al2O3-SiO2 aerogel also shows high hydrophobicity.