Sheaf-like and layered CeO2 with micro/nanocomposite structure were synthesized by a simple and friendly hydrothermal method and used in lean methane combustion. The relationship between the CeO2 structure and catalytic performance in lean methane combustion has been studied by the means of XRD, SEM, TEM&HRTEM, H-2-TPR, BET and XPS. According to the H-TPR results, the reducibility of sheaf-like CeO2 is higher compared with layered CeO2. XPS results reveal that oxygen vacancies are more easily formed on the surface of sheaf-like CeO2 than that on layered CeO2 surface. The catalytic activity of CeO2 in lean methane combustion is strongly related to its morphology; the obtained sheaf-like CeO2 with better reducibility and larger content of Ce3+ exhibits much higher catalytic activity in lean methane combustion compared with the layered CeO2.