The characteristics of ozone decomposition inside the nano-pores of ceramic membranes were identified according to nano-reactor configuration. Three types of ceramic membranes with a pore size of 50 nm were tested with compositions of Al2O3, MnO2/Al2O3 (4%) and CeO2/Al2O3 (4%) respectively. The results showed that the specific decomposition rate of ozone inside membrane pores was 428 times higher than that in pure water outside the pores. The influences of pH values or H2O2 dosages on ozone decomposition in bulk water can be explained on the basis of chain reactions or hydroxyl-radical mechanism; however, these did not work for the behaviours inside the nano-pores of membranes. The extents of the influences of NO3−, SO42− and Ca2+ were even opposite inside to outside the nano-pores of membranes. A unique configuration of nano-reactors within the ceramic membranes tested was proposed based on zeta potentials and water molecule-clusters. Inner charge layer and highly ordered water clusters might play critical roles for the reaction processes inside the nano-reactors.