Hierarchical MoO3 microboxes were successfully prepared via a facile hydrothermal method and use MnCO3 microcubes as the templates. The morphology and structure of as-obtained product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption measurement (BET). The results show that hierarchical MoO3 microboxes possess regular size and morphology, and the size is about 2–3μm, the hierarchical shell of MoO3 microboxes with a thickness of about 150nm. The response value of sensor based on hierarchical MoO3 microboxes to 100ppm ethanol is 78 at an operating temperature of 260°C, and the response and recovery time are less than 15 and 5s, respectively. It is expected that the hierarchical MoO3 microboxes with the advantages of hierarchical structure and hollow structure will become a promising functional material in monitoring and detecting of ethanol.