A one-step hydrothermal route was used to synthesize undoped and Zn-doped SnO₂hierarchical architectures. The morphologies and structures of the as-prepared samples were characterized by X-ray powder diffraction (XRD)，field emission scanning electron microscopy (FESEM)，energy-dispersive X-ray spectroscopy (EDX)，transmission electron microscopy (TEM)，and high-resolution transmission electron microscopy (HRTEM). The results clearly revealed that the as-prepared SnO₂hierarchical architectures were composed of many 2 dimensional (2D) nanosheets with the thickness of about 30 nm. The gas sensing properties of the as-prepared undoped and Zn-doped SnO₂samples were tested toward various gases. The sensor based on S3 (Zn₂+/Sn₄+ = 0.056) showed excellent selectivity toward ethanol at the operating temperature 213 degrees C，giving a response of about 14.4 to 100 ppm，which was about 3.2 times higher than that of sensor based on pure SnO₂.