La0.8Sr0.2MnO3/alpha-Al2O3 shows its potential to be an efficient catalyst for CH4-SCR of NO in our former study. This paper focuses on its activity with water vapor in simulated flue gas and two different pretreatments aimed at improving its performance were also studied. The effects of temperature, residence time and initial O-2 content were investigated by experiment. XRD and SEM results indicate that all three catalysts can remove NO and the vapor-treated catalyst may have the worst behavior due to its poor porous structure. Experiment results show the fresh catalyst can gain a high NO removal rate (> 95%) in certain conditions as well as the other two pretreated catalysts. In general, the NO conversion rates decrease with the increase of the initial O-2 content. The calcined catalyst has the best oxygen resistance ability while the vapor-treated catalyst has the worst tolerance to O-2. NO conversion rates over the calcined catalyst can remain steady above 90% with 0-4% O-2. It seems calcination plays a role in improving the catalytic properties of La0.8Sr0.2MnO3/alpha-Al2O3. This result can provide some information for the practical use of La0.8Sr0.2MnO3 in industry.