Via designing a facile micro-scale all-solid-state lithium-oxygen battery system constructed in an environmental scanning electron microscope, direct visualization of discharge and charge processes of the lithium-oxygen battery is achieved. Different morphologies of the discharge product are observed, including sphere, conformal film and red-blood-cells-like shape, with the particle size up to 1.5 μm; whereas upon charge, the decomposition initiates at their surface and continues along a certain direction, instead of from the contact point at electrode. These new findings indicate that the electron and lithium ion conductivities of Li2O2 could support the growth and decomposition of the discharge product in our system. In addition, our results indicate that various morphologies of Li2O2 arise from different current density and surface chemistry of CNT, and the growth and decomposition of the particle are related to the uneven distribution of the ionic and electronic conductivities of Li2O2.