A reliable in situ self-generating template strategy has been developed for the synthesis of flowerlike carbon nanosheets by hydrothermal carbonization in the presence of both silica and zinc acetate using glucose as the carbon source. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), Raman spectroscopy, nitrogen sorption isotherm measurement (BET) and element analysis revealed the morphology, crystal phase structure, porosity and chemical composition. The formation of the zinc silicate nanosheet template was due to the hydrolysis of amorphous silica and self-assembly under hydrothermal conditions. The resulting flowerlike carbon nanosheets proved to be an excellent palladium catalyst support.