The perovskite catalyst has a good catalytic activity in total oxidation of hydrocacbon, but that catalyst is often poisoned by H2O and SO2 gases. So, it is necessary to prepare the perovskite catalysts which are not poisoned by H2O and SO2 gases. The author studied the preparation and the catalytic properties of La0.7Sr0.3MnO3 perovskite in total oxidation of m-xylelle in previous reports. In present work. The author continue studying of poisoning of La0.7Sr0.3MnO3 perovskite catalyst in this reaction. From investigated results, it is demonstrated that the influence of the H2O gas on catalytic of La0.7Sr0.3MnO3 perovskite is only seen clearly from 200 to 250°C temperature rang. The poisoning of La0.7Sr0.3MnO3 perovskite catalyst increases with increasing of SO2 gas strength, but this poisoning is temporary and the catalytic properties is restored as first after getting into contact with air.