Large-scale single-crystalline SnOznanocauliflowers were successfully synthesized using a hydrothermal growth method without any tem-plate. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), en-ergy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED).FE-SEM images show that the as-grown SnO2 nanocauliflowers are constructed of tetragonal prisms with a width of 500-600 nm. XRD,EDS, and SAED results indicate that the as-grown SnO2 nanocauliflowers are single crystalline with the tetragonal ruffle crystalline structure.The growth mechanism of SnO2 nanocauliflowers is also preliminarily discussed on the basis of different Sn(OH)2-6 concentrations, and it is found that Sn(OH)2-6 concentration plays an important role in determining the shape of the prepared SnO2. Room temperature photolu-minescence was further carried out on SnO2 nanocaulifiowers to investigate their optical properties. An intense blue luminescence centered at a wavelength of 424 nm is observed in the as-grown SnO2 nanocauliflowers.