LaMnO3 catalysts with high catalytic activity for methane combustion have been prepared in an oil-water two-phase system. The procedure was carried out using oleic acid as phase-transfer agent, and ammonia as co-precipitation agent. In the meanwhile, H2O2 is employed to control the valence of Mn ions when precipitation. The control results in perovskites with similar phases having three O-2-TPD patterns, and induces the catalysts possessing distinct catalytic activities. The structure and properties of the catalysts were characterized by BET, TG-DSC, XRD and O-2-TPD techniques.